WDIFF

draft-ietf-calsch-ical-05.txt --> draft-ietf-calsch-ical-06.txt

Network Working Group Frank Dawson, Lotus
Internet Draft Derik Stenerson, Microsoft
<ietf-calsch-ical-05.txt> November 21, 1997
<ietf-calsch-ical-06.txt> March 13, 1998
Expires May September 1998

Internet Calendaring and Scheduling Core Object Specification
(iCalendar)

Status of this Memo

This memo is an Internet-Draft. Internet-Drafts are working documents
of the Internet Engineering Task Force (IETF), its areas, and its
working groups. Note that other groups MAY also distribute working
documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six
months. Internet-Drafts MAY be updated, replaced, or made obsolete by
other documents at any time. It is not appropriate to use Internet-
Drafts as reference material or to cite them other than as a "working
draft" or "work in progress".

To learn the current status of any Internet-Draft, please check the
1id-abstracts.txt listing contained in the Internet-Drafts Shadow
Directories on ds.internic.net (US East Coast), nic.nordu.net
(Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific
Rim).

Distribution of this memo is unlimited.

Abstract

There is a clear need to provide and deploy interoperable calendaring
and scheduling services for the Internet. Current group scheduling
and Personal Information Management (PIM) products are being extended
for use across the Internet, today, in proprietary ways. This memo
has been defined to provide the a definition of a common format for
openly exchanging calendaring and scheduling information across the
Internet.

This memo is formatted as a registration for a MIME media type per
[RFC 2048]. However, the format in this memo is equally applicable
for use outside of a MIME message content type.

The proposed media type value is ''TEXT/CALENDAR''. ''text/calendar''. This string would
label a media type containing calendaring and scheduling information
encoded as text characters formatted in a manner outlined below.

This MIME media type provides a standard content type for capturing
calendar event and event, to-do and journal entry information. It also can be
used to convey free/busy time information. The content type is
suitable as a MIME message entity that can be transferred over MIME
based email systems
or systems, using HTTP. HTTP or some other Internet transport. In addition, the content type is useful as an object

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addition, the content type is useful as an object for interactions
between desktop applications using the operating system clipboard,
drag/drop or file systems capabilities.

This memo is based on the earlier work of the vCalendar specification
for the exchange of personal calendaring and scheduling information.
In order to avoid confusion with this referenced work, this memo is
to be known as the iCalendar specification. This memo is based on

Readers may also wish to refer to the calendaring and scheduling
model defined in []. The document is also
the basis [] for the calendaring and scheduling interoperability
protocol defined in [ITIP]. a description of this Internet application.

This memo also includes defines the format for defining specifying iCalendar object methods.
An iCalendar object method is a set of usage constraints for the
iCalendar object. For example, these methods might define scheduling
messages that request an event be scheduled, reply to an event
request, send a cancellation notice for an event, modify or replace
the definition of an event, provide a counter proposal for an
original event request, delegate an event request to another
individual, request free or busy time, reply to a free or busy time
request, or provide similar scheduling messages for a to-do or
journal entry calendar component. The iCalendar Transport-indendent
Interoperability Protocol (iTIP) defined in [ITIP] is one such
scheduling protocol.

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Table of Contents

1. Introduction........................................................5
2.

1 Introduction.........................................................8
2 Basic Grammar and Conventions.......................................5 Conventions........................................8
2.1 Formatting Conventions ...........................................6 ...........................................9
2.2 Related Memos ....................................................7
3. ...................................................10
3 TEXT/CALENDAR Registration Information..............................7
4. Information..............................10
4 iCalendar Object Specification......................................9 Specification......................................13
4.1 Content Considerations ...........................................9
4.1.1 Content Lines ................................................10
4.1.2 ...................................................13
4.1.1 List and Field Separators ....................................12
4.1.3 ....................................16
4.1.2 Multiple Values ..............................................13
4.1.4 ..............................................16
4.1.3 Binary Content ...............................................13
4.1.5 ...............................................17
4.1.4 Character Set ................................................17
4.2 Property Parameters ..........................................13
4.1.6 .............................................17
4.2.1 Alternate Text Representation ................................14
4.1.7 Character Set ................................................14
4.1.8 ................................18
4.2.2 Inline Encoding ..............................................15
4.1.9 ..............................................19
4.2.3 Language .....................................................15
4.1.10 .....................................................19
4.2.4 Time Zone Identifier .........................................20
4.2.5 Value Data Types ............................................15
4.2 iCalendar object ................................................25 .............................................21
4.3 Property Value Data Types .......................................21
4.3.1 Binary .......................................................22
4.3.2 Boolean ......................................................22
4.3.3 Calendar User Address ........................................23
4.3.4 Date .........................................................23
4.3.5 Date-Time ....................................................24
4.3.6 Duration .....................................................25
4.3.7 Float ........................................................26
4.3.8 Integer ......................................................27
4.3.9 Period of Time ...............................................27
4.3.10 Recurrence Rule .............................................28
4.3.11 Text ........................................................33
4.3.12 Time ........................................................34
4.3.13 URI .........................................................36
4.3.14 UTC Offset ..................................................36
4.4 iCalendar Object ................................................37
4.5 Property ........................................................38
4.6 Calendar Components .............................................26
4.4.1 .............................................38
4.6.1 Event Component ..............................................26
4.4.2 ..............................................38
4.6.2 To-do Component ..............................................28
4.4.3 ..............................................40
4.6.3 Journal Component ............................................29
4.4.4 ............................................41
4.6.4 Free/Busy Component ..........................................30
4.4.5 Alarm Component ..............................................31
4.4.6 ..........................................43
4.6.5 Timezone Component ...........................................33
4.5 ...........................................45
4.6.6 Alarm Component ..............................................50
4.7 Calendar Properties .............................................37
4.5.1 .............................................53
4.7.1 Calendar Scale ...............................................37
4.5.2 ...............................................54
4.7.2 Method .......................................................37
4.5.3 .......................................................54
4.7.3 Product Identifier ...........................................38
4.5.4 Source .......................................................38
4.5.5 Source Name ..................................................39
4.5.6 ...........................................55
4.7.4 Version ......................................................39
4.6 ......................................................56
4.8 Component Properties ............................................40
4.6.1 ............................................56
4.8.1 Descriptive Component Properties .............................56
4.8.1.1 Attachment ...................................................40
4.6.2 Attendee .....................................................40
4.6.3 ...............................................56
4.8.1.2 Categories ...................................................43
4.6.4 Classification ...............................................44
4.6.5 Comment ......................................................44
4.6.6 Contact ......................................................45
4.6.7 Date/Time Completed ..........................................45
4.6.8 Date/Time Created ............................................46
4.6.9 Date/Time Due ................................................46
4.6.10 Date/Time End ...............................................46
4.6.11 Date/Time Stamp .............................................47
4.6.12 Date/Time Start .............................................47
4.6.13 Daylight ....................................................48
4.6.14 Description .................................................48
4.6.15 Duration ....................................................49
4.6.16 Exception Date/Times ........................................50
4.6.17 Exception Rule ..............................................50 ...............................................57

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4.6.18 Free/Busy Time ..............................................51
4.6.19 March 6, 1998

4.8.1.3 Classification ...........................................58
4.8.1.4 Comment ..................................................59
4.8.1.5 Description ..............................................59
4.8.1.6 Geographic Position .........................................52
4.6.20 Last Modified ...............................................53
4.6.21 ......................................60
4.8.1.7 Location ....................................................53
4.6.22 .................................................61
4.8.1.8 Percent Complete ............................................54
4.6.23 .........................................61
4.8.1.9 Priority ....................................................54
4.6.24 Recurrence Date/Times .......................................55
4.6.25 Recurrence ID ...............................................56
4.6.26 Recurrence Rule .............................................57
4.6.27 Related To ..................................................64
4.6.28 Repeat Count ................................................65
4.6.29 Request Status ..............................................66
4.6.30 .................................................62
4.8.1.10 Resources ...................................................67
4.6.31 Sequence Number .............................................68
4.6.32 ...............................................63
4.8.1.11 Status ......................................................68
4.6.33 ..................................................64
4.8.1.12 Summary .....................................................69
4.6.34 Time Transparency ...........................................69
4.6.35 Time Zone Name ..............................................70
4.6.36 .................................................65
4.8.2 Date and Time Zone Offset ............................................70
4.6.37 Uniform Resource Locator ....................................70
4.6.38 Unique Component Properties ...........................66
4.8.2.1 Date/Time Completed ......................................66
4.8.2.2 Date/Time End ............................................66
4.8.2.3 Date/Time Due ............................................67
4.8.2.4 Date/Time Start ..........................................68
4.8.2.5 Duration .................................................69
4.8.2.6 Free/Busy Time ...........................................69
4.8.2.7 Time Transparency ........................................71
4.8.3 Time Zone Component Properties ...............................72
4.8.3.1 Time Zone Identifier .....................................72
4.8.3.2 Time Zone Name ...........................................72
4.8.3.3 Time Zone Offset From ....................................73
4.8.3.4 Time Zone Offset To ......................................74
4.8.3.5 Time Zone URL ............................................74
4.8.4 Relationship Component Properties ............................75
4.8.4.1 Attendee .................................................75
4.8.4.2 Contact ..................................................78
4.8.4.3 Organizer ................................................79
4.8.4.4 Recurrence ID ............................................80
4.8.4.5 Related To ...............................................81
4.8.4.6 Uniform Resource Locator .................................82
4.8.4.7 Unique Identifier ...........................................71
4.6.39 ........................................83
4.8.5 Recurrence Component Properties ..............................84
4.8.5.1 Exception Date/Times .....................................84
4.8.5.2 Exception Rule ...........................................85
4.8.5.3 Recurrence Date/Times ....................................86
4.8.5.4 Recurrence Rule ..........................................88
4.8.6 Alarm Component Properties ...................................95
4.8.6.1 Alarm Type ...............................................96
4.8.6.2 Repeat Count .............................................96
4.8.6.3 Trigger ..................................................97
4.8.7 Change Management Component Properties .......................98
4.8.7.1 Date/Time Created ........................................98
4.8.7.2 Date/Time Stamp ..........................................99
4.8.7.3 Last Modified ............................................99
4.8.7.4 Sequence Number .........................................100
4.8.8 Miscellaneous Component Properties ..........................101
4.8.8.1 Non-standard Properties .....................................72
5. .................................101
4.8.8.2 Request Status ..........................................102
5 iCalendar Object Examples..........................................103
6 Recommended Practices..............................................72
6. Practices..............................................107
7 Registration of Content Type Elements..............................73
6.1 Elements..............................107
7.1 Registration of New and Modified iCalendar object Object Methods .......73
6.2 ......107
7.2 Registration of New Properties ..................................73
6.2.1 .................................108

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7.2.1 Define the property ..........................................73
6.2.2 .........................................108
7.2.2 Post the Property definition .................................74
6.2.3 ................................109
7.2.3 Allow a comment period .......................................74
6.2.4 ......................................109
7.2.4 Submit the property for approval .............................74
6.3 ............................109
7.3 Property Change Control .........................................75
7. File extension.....................................................75
8. Macintosh File Type Code...........................................75
9. References.........................................................75
10. Acknowledgments...................................................77
11. ........................................109
8 References.........................................................109
9 Acknowledgments....................................................111
10 Author's Address..................................................77
12. iCalendar object Examples.........................................78
13. Address..................................................111
11 Full Copyright Statement..........................................80 Statement..........................................112

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1. March 6, 1998

1 Introduction

The use of calendaring and scheduling has grown considerably in the
last decade. Enterprise and inter-enterprise business has become
dependent on rapid scheduling of events and actions using this
information technology. However, the longer term growth of
calendaring and scheduling, is currently limited by the lack of
Internet standards for the message content types that are central to
these groupware knowledgeware applications. This memo is intended to progress
the level of interoperability possible between dissimilar calendaring
and scheduling applications. This memo defines a MIME content type
for exchanging electronic calendaring and scheduling information. The
Internet Calendaring and Scheduling Core Object Specification, or
iCalendar, allows for the capture and exchange of information
normally stored within a calendaring and scheduling application; such
as a Personal Information Manager (PIM) or a Group Scheduling
product.

The calendaring and scheduling model implemented by this memo is model, defined in the [ICMS]. [ICMS], is a
useful reference to terms and the general framework of this Internet
application.

The iCalendar format is suitable as an exchange format between
applications or systems. The format is defined in terms of a MIME
content type. This will enable the object to be exchanged using
several transports, including but not limited to SMTP, HTTP, a file
system, desktop interactive protocols such as the use of a memory-based memory-
based clipboard or drag/drop interactions, point-to-point
asynchronous communication, wired-network transport, or some form of
unwired transport such as infrared might also be used.

The definition of a calendaring and scheduling interoperability
protocol is the subject of another memo [ITIP].

The memo also provides for the definition of iCalendar object methods
that will map this content type to a set of messages for supporting
calendaring and scheduling operations such as requesting, replying
to, modifying, and canceling meetings or appointments, to-dos and
journal entries. The iCalendar object methods can be used to define
other calendaring and scheduling operations such a requesting for and
replying with free/busy time data. Such a scheduling protocol is
defined in the iCalendar Transport-independent Interoperability
Protocol (iTIP) defined in [ITIP].

The memo also includes a formal grammar for the content type to aid based on
the Internet ABNF defined in [RFC 2234]. This ABNF is required for
the implementation of parsers and to serve as the definitive
reference when ambiguities or questions arise in interpreting the
descriptive prose definition of the memo.

2 Basic Grammar and Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this
document are to be interoperated as described in [RFC 2119].

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This memo makes use of both a descriptive prose and a more formal
notation for defining the calendaring and scheduling format.

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The notation used in this memo is the augmented BNF ABNF notation of [RFC
822]. 2234].
Readers intending on implementing this format defined in this memo
should be familiar with this notation in order to properly interpret
the specifications of this memo.

All numeric and hexadecimal values used in this memo are given in
decimal notation. All names of properties, property parameters,
enumerated property values and property parameter values are case-
insensitive. However, all other property values are case-sensitive,
unless otherwise stated.

Note: All indented editorial notes, such as this one, are
intended to provide the reader with additional information that
is not essential to the building of a conformant implementation
of the specifications of this memo. The information is provided
to highlight a particular feature or characteristic of the
specifications.

The format for the iCalendar object is based on the syntax of the
[MIME DIR] content type. While the iCalendar object is not a profile
of the [MIME DIR] content type, it does reuse a number of the
elements from the [MIME DIR] specification.

2.1 Formatting Conventions

The mechanisms defined in this memo are defined in propose. Many of
the terms used to describe these have common usage that is different
than the standards usage of this memo. In order to refer to reference within
this memo elements of the calendaring and scheduling model [ICMS],
core object (this memo) or interoperability protocol [ITIP] in this
memo some
formatting conventions have been used. Calendaring and scheduling
roles defined by [ICMS] are referred to in quoted-strings of text
with the first character of each word in upper case. For example,
"Organizer" refers to a role of a "Calendar User" within the
scheduling protocol defined by [ITIP] Calendar components defined by
this memo are referred to with capitalized, quoted-strings of text.
All calendar components start with the letter "V". For example,
"VEVENT" refers to the event calendar component, "VTODO" refers to
the to-do calendar component and "VJOURNAL" refers to the daily
journal calendar component. Scheduling methods defined by [ITIP] are
referred to with capitalized, quoted-strings of text. For example,
"REQUEST" refers to the method for requesting a scheduling calendar
component be created or modified, "REPLY" refers to the method a
recipient of a request uses to update their status with the
"Organizer" of the calendar component.

The properties defined by this memo are referred to with capitalized,
quoted-strings of text, followed by the word "property". For example,
"ATTENDEE" property refers to the iCalendar property used to convey
the calendar address of a calendar user. Property parameters defined
by this memo are referred to with lower case, quoted-strings of text,

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followed by the word "parameter". For example, "value" parameter
refers to the iCalendar property parameter used to override the
default data type for a property value. Enumerated values defined by
this memo are referred to with capitalized text, either alone or
followed by the word "value". For example, the "MINUTELY" value can

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be used with the "FREQ" component of the "RECUR" data type to specify
repeating components based on an interval of one minute or more.

2.2 Related Memos

Implementers will need to be familiar with several other memos that,
along with this memo, form a framework for Internet calendaring and
scheduling standards. This memo, [ICAL], specifies a core
specification of objects, data types, properties and property
parameters.

[ICMS] - specifies a common terminology and abstract; abstract model;

[ITIP] - specifies an interoperability protocol for scheduling
between different implementations;

[IMIP] specifies an Internet email binding for [ITIP];

[IRIP] - specifies an Internet real time protocol binding for [ITIP].

This memo does not attempt to repeat the specification of concepts or
definitions from these other memos. Where possible, references are
made to the memo that provides for the specification of these
concepts or definitions.

3 TEXT/CALENDAR Registration Information

The Calendaring and Scheduling Core Object Specification is intended
for use as a MIME content type. However, the implementation of the
memo is in no way limited solely as a MIME content type.

The following text is intended to register this memo as the MIME
content type "text/calendar".

To: ietf-types@uninett.no

Subject: Registration of MIME content type text/calendar.

MIME media type name: text

MIME subtype name: calendar

Required parameters: none

Optional parameters: charset, method and component

The "charset" parameter is defined in [RFC 2046] for other body
parts. It is used to identify the default character set used within
the body part.

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The "method" parameter is used to convey the iCalendar object
method to which or transaction semantics for the calendaring and scheduling information
pertains.
information. It also is an identifier for the restricted set of
properties and values that the iCalendar object will consist consists of. The
parameter is to be used as a guide for applications interpreting
the information contained within the body part. It should SHOULD NOT be
used to exclude or require particular pieces of information unless
the identified method definition specifically calls for this
behavior. Unless specifically forbidden by a particular method
definition, a text/calendar content type MAY contain any set of
properties

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Specification. The "method" parameter MUST be the same value as
that specified in the "METHOD" component property in the iCalendar
object. If one is present, the other must also be present.

The value for the "method" parameter is defined as follows:

method = 1*(ALPHA / DIGIT / "-")
; IANA registered iCalendar object method

Optional parameters: charset, component

The "charset" parameter is defined in [RFC 2046] for other body
parts. It is used to identify the default character set used within
the body part.

The "component" parameter conveys the type of iCalendar calendar
component within the body part. If the iCalendar object contains
more than one calendar component, then the different components are
each specified
as once in a comma-separated list of values.

The value for the "component" parameter is defined as follows:

component = "VEVENT" ("VEVENT" / "VTODO" / "VJOURNAL" / "VFREEBUSY"
/ "VTIMEZONE" / x-name / iana-token iana-token) ["," [WSP]
component]

Optional content header fields: Any header fields defined by [RFC
2045].

Encoding considerations: This MIME content type can contain 8bit
characters, so the use of quoted-printable or base64 MIME content-
transfer-encodings MAY be necessary when iCalendar objects are
transferred across protocols restricted to the 7bit repertoire.
Note that each a text valued property in the content entity MAY also
have content encoding of special characters encoded using a BACKSLASH
character (ASCII decimal 92) escapement technique. This means that
content values MAY end up encoded twice.

Security considerations: SPOOFING - - In this memo, the "Organizer"
is the only person authorized to make changes to an existing
"VEVENT", "VTODO", "VJOURNAL" calendar component and redistribute
the updates to the "Attendees". An iCalendar object that
maliciously changes or cancels an existing "VEVENT", "VTODO" or
"VJOURNAL" or "VFREEBUSY" calendar component MAY be constructed by
someone other than the "Organizer" and sent to the "Attendees". In
addition in this memo, other than the "Organizer", an "Attendee" of
a "VEVENT", "VTODO", "VJOURNAL" calendar component is the only
other person authorized to update any parameter associated with
their "ATTENDEE" property and send it to the "Organizer". An

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iCalendar object that maliciously changes the "ATTENDEE" parameters
MAY be constructed by someone other than the real "Attendee" and
sent to the "Organizer".

PROCEDURAL ALARMS - - An iCalendar object can be created that
contains a "VEVENT" and "VTODO" calendar component with an "VALARM"
calendar components. The "VALARM" calendar component MAY be of type
PROCEDURE and MAY have an attachment containing some sort of

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executable program. Implementations that incorporate these types of
alarms are subject to any virus or malicious attack that MAY occur
as a result of executing the attachment.

ATTACHMENTS - - An iCalendar object MAY include references to
Uniform Resource Locators that MAY be programmed resources.

Implementers and users of this memo should be aware of the network
security implications of accepting and parsing such information. In
addition, the security considerations observed by implementations
of electronic mail systems should be followed for this memo.

Interoperability considerations: This MIME content type is intended
to define a common format for conveying calendaring and scheduling
information between different systems. It is heavily based on the
earlier [VCAL] industry specification.

Intended Usage: COMMON

Published specification:

Applications which use this media type: This memo.

Author/Change controllers:

Frank Dawson
6544 Battleford Drive
Raleigh, NC 27613-3502
919-676-9515 (Telephone)
919-676-9564 (Data/Facsimile)
Frank_Dawson@Lotus.com (Internet Mail)

Derik Stenerson
One Microsoft Way
Redmond, WA 98052-6399
425-936-5522 (Telephone)
425-936-7329 (Facsimile)
deriks@microsoft.com (Internet Mail)

4. content-type is
designed for widespread use by Internet calendaring and scheduling
applications. In addition, applications in the workflow and
document management area may find this content-type applicable. The
[ITIP], [IMIP] and [IRIP] Internet protocols directly use this
content-type also. Future work on an Internet calendar access
protocol will utilize this content-type too.

Additional information: This memo defines this content-type.

Magic numbers: None.

File extensions: The file extension of "ics" is to be used to
designate a file containing an arbitrary set of calendaring and
scheduling information consistent with this MIME content type.

The file extension of "ifb" is to be used to designate a file
containing free or busy time information consistent with this MIME
content type.

Macintosh file type codes: The file type code of "ical" is to be
used in Apple MacIntosh operating system environments to designate
a file containing calendaring and scheduling information consistent
with this MIME media type.

The file type code of "ifb" is to be used in Apple MacIntosh
operating system environments to designate a file containing free
or busy time information consistent with this MIME media type.

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Person & email address to contact for further information:

Frank Dawson
6544 Battleford Drive
Raleigh, NC 27613-3502
919-676-9515 (Telephone)
919-676-9564 (Data/Facsimile)
Frank_Dawson@Lotus.com (Internet Mail)

Derik Stenerson
One Microsoft Way
Redmond, WA 98052-6399
425-936-5522 (Telephone)
425-936-7329 (Facsimile)
deriks@microsoft.com (Internet Mail)

Intended usage: COMMON

Author/change controller:

Frank Dawson
6544 Battleford Drive
Raleigh, NC 27613-3502
919-676-9515 (Telephone)
919-676-9564 (Data/Facsimile)
Frank_Dawson@Lotus.com (Internet Mail)

Derik Stenerson
One Microsoft Way
Redmond, WA 98052-6399
425-936-5522 (Telephone)
425-936-7329 (Facsimile)
deriks@microsoft.com (Internet Mail)

4 iCalendar Object Specification

The following sections define the details of a Calendaring and
Scheduling Core Object Specification. This information is intended to
be an integral part of the MIME content type registration. In
addition, this information MAY be used independent of such content
registration. In particular, this memo has direct applicability for
use as a calendaring and scheduling exchange format in file-, memory-
or network-based transport mechanisms.

4.1 Content Considerations Lines

The iCalendar object consists of is organized into individual lines of text. This section defines
how the content lines MUST be formatted.

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4.1.1 text,
called content lines. Content Lines

The iCalendar object consists of individual lines of text, are delimited by a line break,
which is a CRLF sequence (ASCII decimal 13, followed by ASCII decimal
10).

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Lines of text should not SHOULD NOT be longer than 76 75 characters, excluding the
line break. Long content lines of text can SHOULD be split into a multiple line
representations using a line "folding" technique. That is, a long
line MAY be split at any point by inserting a CRLF immediately
followed by a single linear white space character (i.e., SPACE, ASCII
decimal 32 or HTAB, ASCII decimal 9). Any sequence of CRLF followed
immediately by a single linear white space character is ignored
(i.e., removed) when processing the content type.

For example the line:

DESCRIPTION:This is a long description that exists on a long line.

Can be represented as:

DESCRIPTION:This is a long lo
ng description
that exists on a long line.

The process of moving from this folded multiple line representation
to its single line representation is called "unfolding". Unfolding is
accomplished by removing the CRLF character and the linear white
space character that immediately follows.

An intentional formatted text line break MAY only be included in

When parsing a
property value by representing the line break with content line, folded lines must first be unfolded
according to the character
sequence of BACKSLASH (ASCII decimal 92), followed by a LATIN SMALL
LETTER N (ASCII decimal 110) or a LATIN CAPITAL LETTER N (ASCII
decimal 78), that is "\n" or "\N".

For example unfolding procedure described above. When generating
a multiple line "DESCRIPTION" property value of:

Project XYZ Final Review
Conference Room - 3B
Come Prepared.

Could content line, lines longer than 75 characters SHOULD be represented as:

DESCRIPTION:Project_XYZ Final_Review\n
Conference Room - 3B\nCome_Prepared. folded
according to the folding procedure described above.

The content information associated with an iCalendar object is
formatted using a syntax similar to that defined by [MIME DIR]. That
is, the content information consists of one or more CRLF-separated
content lines as defined by the lines.

The following notation: notation defines the defines the lines of content in an
iCalendar object:

contentline = name *(";" [WSP] param ) ":" [WSP] value-list value CRLF
; Lines This ABNF is just a general definition for an initial parsing
; of the content line into its property name, parameter list,
; and value string

; When parsing a content line, folded lines must first
; be unfolded according to the unfolding procedure
; described above. When generating a content line, lines
; longer than 75 characters should SHOULD be folded

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; the folding procedure described above.

name = iana-token / x-name

x-name = "X-" 1*(ALPHA / iana-token

iana-token = 1*(ALPHA / DIGIT / "-")
; iCalendar identifier registered with IANA

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x-name = "X-" 1*(ALPHA / DIGIT / "-")
;Reservered
; Reservered for experimental use. Not intended for use in
; released products.

param = param-name "=" param-value
*("," param-value)

param-name = iana-token

param-value = quoted-string / text

value-list = value-struct *([FOLD] "," value-struct)
; permitted values are restricted by valuetype

value-struct = value-elem *([FOLD] ";" value-elem)

value-elem = folded-text / folded-b Each property defines the specific ABNF for the parameters
; encoding determined by encoding allowed on the property. Refer to specific properties for
; precise parameter ABNF.

param-name = iana-token

param-value = 1*(ALPHA / DIGIT paramtext / "-")
; iCalendar identifier registered with IANA

text quoted-string

paramtext = *SAFE-CHAR

quoted-string

value = DQUOTE *(QSAFE-CHAR / QUOTED-CHAR) DQUOTE

folded-text *VALUE-CHAR

quoted-string = *([FOLD] (SAFE-CHAR / ":" / DQUOTE / ESCAPED-CHAR))

folded-base64 = *([FOLD] 4B-CHAR) [[FOLD] b-end]

base64-end = (2B-CHAR "==") / (3B-CHAR "=")

ESCAPED-CHAR = "\" ("\" / *qtext DQUOTE / ";" / "," / "N" / "n")
; \\ encodes \, \" encodes ", \N or \n encodes newline
; \; encodes ;, \, encodes ,

B-CHAR

qtext = ALPHA / DIGIT / "+" QSAFE-CHAR / "/"

FOLD = CRLF WSP
; not considered part of the value QUOTED-CHAR

NON-ASCII = %x80-FF
; use Use restricted by charset parameter
; on outer MIME object (UTF-8 preferred)

QSAFE-CHAR = %x20-21 WSP / %x21 / %x23-5B / %x5D-7E / NON-ASCII
; Any character except CTLs, DQUOTE, or "\"

QUOTED-CHAR = "\" ("\" / "," / DQUOTE)
; \\ encodes \, \" encodes "

SAFE-CHAR = %x20-21 WSP / %x21 / %x23-2B / %x2D-39 / %x3C-5B
%x5D-7E %x3C-7E
/ NON-ASCII
; Any character except CTLs, DQUOTE, ";", ":", "\", ","

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ALPHA

VALUE-CHAR = %x41-5A / %x61-7A ; A-Z WSP / a-z

BIT = "0" VCHAR / "1"

CHAR NON-ASCII
; Any textual character

VCHAR = %x01-7F %x21-7E
; any 7-bit US-ASCII character, excluding NUL visible (printing) characters

CR = %x0D
; carriage return

LF = %x0A

CRLF = CR LF
; Internet standard newline

CTL = %x00-1F / %x7F
; controls Controls

ALPHA = %x41-5A / %x61-7A ; A-Z / a-z

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DIGIT = %x30-39
; 0-9DQUOTE 0-9

DQUOTE = %x22
; Quotation Mark

WSP = SPACE / HTAB

SPACE = %x20

HTAB = %x09

4.1.2 List and Field Separators

List of values MAY be specified for property values or

The property
parameter values. Each value in component of a content line has a format that is
property specific. Refer to the section describing each property for
a definition of this format.

4.1.1 List and Field Separators

List of values MAY be specified for property values or property
parameter values. Each value in a list of values MUST be separated by
a COMMA character (ASCII decimal 44).

Some property values are defined in terms of multiple components.
These structured property values MUST have their components separated
by a SEMICOLON character (ASCII decimal 59).

Lists of property parameters MAY be specified for a property. Each
property parameter in a list of property parameters MUST be separated
by a SEMICOLON character (ASCII decimal 59).

A COLON character in a property value does not need to be escaped
with a BACKSLASH character.

A BACKSLASH character (ASCII decimal 92) in a property value MUST be
escaped with another BACKSLASH character. A COMMA character in a
property value MUST be escaped with a BACKSLASH character (ASCII
decimal 92). A SEMICOLON character in a property value MUST be
escaped with a BACKSLASH character (ASCII decimal 92).

Property parameters with values containing a COLON, a SEMICOLON or a
COMMA character must be placed in quoted text string.

For example, in the following properties a SEMICOLON is used to
separate property parameters and property value fields. A COMMA is
used to separate values.

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ATTENDEE;RSVP=TRUE;ROLE=ATTENDEE:MAILTO:J.Smith <jsmith@host.com>

ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:MAILTO:
jsmith@host.com

RDATE;VALUE=DATE:19970304,19970504,19970704,19970904

4.1.3

4.1.2 Multiple Values

Each property

Some properties defined in the iCalendar object MAY have multiple
values, if allowed in the definition of the specific property.
values. The general rule for encoding multi-valued items is to simply
create a new content line for each value; including the property
name. However, it should be noted that some properties support
encoding multiple values in a single property by separating the
values with a COMMA character (ASCII decimal 44).

4.1.4

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4.1.3 Binary Content

Binary content information in an iCalendar object SHOULD be
referenced using a URI within a property value. That is the binary
content information SHOULD be placed in an external MIME entity that
can be referenced by a URI from within the iCalendar object. In
addition,
applications where this is not feasible, binary content information
MAY be included within an iCalendar object, but only after first
encoding it into text using the "B" encoding method defined in [RFC
2047]. Support for inline binary content SHOULD be restricted to
those applications requirements that necessitate conveying the
complete calendaring and scheduling information within a single
iCalendar object. A property containing inline binary content
information MUST specify the "ENCODING" property parameter. Binary
content information placed external to the iCalendar object MUST be
referenced by a uniform resource identifier (URI).

The following example specifies an "ATTACH" property that references
an attachment external to the iCalendar object with a URI reference:

ATTACH:http://xyz.com/public/quarterly-report.doc

The following example specifies an "ATTACH" property with inline
binary encoded content information:

ATTACH;ENCODING=b;VALUE=text:MIICajCCAdOgAwIBAgICBEUwDQYJKoZI

ATTACH;ENCODING=b;VALUE=binary:MIICajCCAdOgAwIBAgICBEUwDQYJKoZI
hvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENv
bW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlv
biBTeXN0 <...remainder of "B" encoded binary data...>

4.1.5

4.1.4 Character Set

There is not a property parameter to declare the character set used
in a property value. The default character set for an iCalendar
object is [UTF-8].

The "charset" Content-Type parameter MAY be used in MIME transports
to specify any other IANA registered character set.

4.2 Property Parameters

A property MAY have additional attributes associated with it. These
"property parameters" contain meta information about the property or
the property value. Property parameters MAY be used to specify the
location of an alternate text representation for a property value,
the language of a text property value or the data type of the
property value.

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property-specific parameters that apply only to that property.

Property parameter values that contain the COLON, SEMICOLON, COMMA or
BACKSLASH character separators MUST be specified as quoted-string
text values. For example:

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DESCRIPTION;ALTREP="http://www.wiz.org":The Fall'98 Wild Wizards
Conference - - Las Vegas, NV, USA

The general property parameters defined by

Property parameter values that are not in quoted strings are case
insensitive.

The general property parameters defined by this memo are specified
the following notation:

parameter = altrepparm ;Alternate text representation
/ encodingparm ;Inline encoding
/ languageparm ;Text ;National language for text
/ tzidparm ;Reference to time zone object
/ valuetypeparm ;Property value data type

4.1.6
/ iana-token
;Some other IANA registered iCalendar parameter, such as those
;defined by an individual property.
/ x-name
;A non-standard, experimental parameter

4.2.1 Alternate Text Representation

Parameter Name: ALTREP

Purpose: To specify an alternate text representation for the property
value.

Conformance: Optional

Format Definition: The "ALTREP" property parameter is an OPTIONAL property parameter. It
specifies defined by the following
notation:

altrepparm = "altrep" "=" DQUOTE uri DQUOTE

Description: The parameter specifies a URI that points to an
alternate representation for a textual property value. The A property
specifying this parameter MUST also include a value that reflects the
default representation.

This property parameter MAY include multiple values, separated by the
COMMA character (ASCII decimal 44). The property parameter MAY only
be specified in the "COMMENT", "CONTACT", "DESCRIPTION", "LOCATION"
and "SUMMARY" properties.

For example:

Example:

DESCRIPTION;ALTREP="CID:<part3.msg.970415T083000@host.com>":Project
XYZ Review Meeting will include the following agenda items: (a)
Market Overview, (b) Finances, (c) Project Management

The "ALTREP" property parameter value might point to a "text/html"
content portion.

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Content-Type:text/html
Content-Id:<part3.msg.970415T083000@host.com>

<p><b>Project XYZ Review Meeting</b> will include the following
agenda items:<li>Market
Overview</li><li>Finances</li><li>Project Management</li></p>

4.2.2 Inline Encoding

Parameter Name: ENCODING

Purpose: To specify an alternate inline encoding for the property
value.

Conformance: Required, if the inline encoding is not "8bit".

Format Definition: The "ALTREP" property parameter is defined by the following
notation:

altrepparm

encodingparm = "altrep" "encoding" "=" uri

4.1.7 Character Set

There "8bit"
;"8bit" text encoding is not a property parameter to declare the character set used defined in a property value. The default character set for an iCalendar
object [RFC 2045]
/ "b"
;"b" binary encoding format is [UTF-8].

The "charset" Content-Type parameter MAY be used defined in MIME transports
to specify any [RFC 2047]
/ iana-token
;Some other IANA registered character set.

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4.1.8 Inline Encoding iCalendar encoding type
/ x-name
;A non-standard, experimental encoding type

Description: The "ENCODING property parameter is an OPTIONAL property
parameter. It identifies the inline encoding used in a property
value. The default encoding type is "8bit", corresponding to a
property value consisting of text. The "b" encoding type corresponds
to a property value encoded using the "B" encoding defined in [RFC
2047].

If the value type parameter is ";VALUE=BINARY", then the inline
encoding parameter MUST be specified with the value ";ENCODING=B".

4.2.3 Language

Parameter Name: LANGUAGE

Purpose: To specify the national language for text values in a
property or property parameter.

Conformance: Optional. There is no default national language for a
text value.

Format Definition: The "ENCODING" property parameter is defined by the following
notation:

encodingparam

languageparm = "encoding" "language" "=" "8bit" / "b" / iana-token
/ x-name
;"8bit" text encoding is defined in [RFC 2045]
;"b" binary encoding format is language

language = <Text identifying a language, as defined in [RFC 2047]
;Some other IANA registered iCalendar encoding type
;A non-standard, experimental encoding type

4.1.9 Language 1766]>

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Description: The "LANGUAGE" property parameter is an OPTIONAL property parameter.
It identifies the national language used in of the
text values. in the property or property parameter value. The value of the
"language" property parameter is that defined in [RFC 1766].

Note: For transport in a MIME entity, the Content-Language
header field MAY be used to set the default language for the
entire body part.

The "LANGUAGE"

Example:

SUMMARY;LANGUAGE=us-EN:Company Holiday Party

ATTENDEE;CN=Henri Weisz;LANGUAGE=ca-FR:hweisz@host.com

4.2.4 Time Zone Identifier

Parameter Name: TZID

Purpose: To specify the identifier for the time zone definition for a
time value.

Conformance: Optional

Format Definition: This property parameter is defined by the
following notation:

languageparm

tzidparm = "language" "TZID" "=" language

language [tzidprefix] paramtext CRLF

tzidprefix = <Text identifying a language, as defined in [RFC 1766]>

4.1.10 Value Data Types "/"

Description: The "VALUE" property parameter MAY only be used on the "DTSTART",
"DTEND", "DUE", "EXDATE" and "RDATE " properties when either a DATE-
TIME or TIME value type is an OPTIONAL specified. This property parameter. It
is used parameter
specifies a text value which uniquely identifies the "VTIMEZONE"
calendar component to identify be used when evalating the data type and format time portion of the property value.
property. The values value of a the TZID property MUST parameter will be equal to
the value of the TZID property for the matching "TIMEZONE" object.
The presence of the SOLIDUS character (ASCII decimal 47) as a single data type. For example, prefix,
indicates that this TZID represents a "RDATE" property cannot have unique ID in a combination globally defined
time zone registry (when such registry is defined).

The following are examples of this property parameter:

DTSTART;TZID=America-New_York:19980119T020000

DTEND;TZID=America-New_York:19980119T030000

The TZID property parameter MUST NOT be applied to DATE-TIME and nor TIME
values.
properties whose time values are specified in UTC.

The "VALUE" use of local time in a DATE-TIME or TIME value without the TZID
property parameter is defined to be interpreted as a local time value,
regardless of the existence of "VTIMEZONE" calendar components in the
iCalendar object.

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For more information see the sections on the data types DATE-TIME and
TIME.

4.2.5 Value Data Types

Parameter Name: VALUE

Purpose: To explicitly specify the data type format for a property
value.

Conformance: Optional if using the default value type in a property
value. Otherwise, it is required.

Format Definition: The "VALUE" property parameter is defined by the
following notation:

valuetypeparm = "value" "=" valuetype

valuetype = "binary"
/ "boolean"
/ "cal-address"
/ "date"
/ "date-time"
/ "duration"
/ "float"
/ "integer"

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/ "period"
/ "recur"
/ "text"
/ "time"
/ "uri"
/ "utc-offset"
/ x-name
;Some experimental iCalendar data type.
/ iana-token
;Some other IANA registered iCalendar data type.

Description: The following data types are defined by this memo.

4.1.10.1 Boolean

The "BOOLEAN" data type parameter is used to identify properties that contain
either a "true" or a "false" boolean value. These values are case
insensitive. The the data type is defined by the following notation:

boolean = "TRUE" / "FALSE"

For example, any and
format of the following are equivalent:

TRUE
true
TrUe

4.1.10.2 Calendar User Address property value. The "CAL-ADDRESS" data type is used to identify properties that
contain an address property values MUST be of a calendar user. The single
value is type. For example, a URI as defined
by [RFC 1738] or any other IANA registered form for "RDATE" property cannot have a URI. When used
to address combination
of DATE-TIME and TIME value types.

4.3 Property Value Data Types

The properties in an Internet email transport address for a calendar user, iCalendar object are strongly typed. The
definition of each property restricts the value MUST to be a MAILTO URI, as one of the
value data types, or simply value types, defined by [RFC 1738]. in this section. The data
value type is for a property will either be specified implicitly as defined by the following notation:

cal-address = uri

4.1.10.3 Date

The "DATE" data
default value type is used to identify values that contain a
calendar date. The format is expressed as the [ISO 8601] complete
representation, basic format for a calendar date. The text format
specifies a four-digit year, two-digit month, and two-digit day of or will be explicitly specified with the month. There are no separator characters between "VALUE"
parameter. If the year, month
and day component text. The data value type of a property is defined by one of the following
notation:

date-fullyear = 4DIGIT
date-month = 2DIGIT ;01-12
date-mday = 2DIGIT ;01-28, 01-29, 01-30, 01-31
;based on month/year

date = date-fullyear date-month date-mday alternate
valid types, then it MUST be explicitly specified with the "VALUE"
parameter.

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For example, the following represents July 14, 1997:

19970714

4.1.10.4 Date-Time

The "DATE-TIME" data March 6, 1998

4.3.1 Binary

Value Name: BINARY

Purpose: This value type is used to identify values properties that contain
a
precise calendar date and time of day. The format is expressed as the
[ISO 8601] complete representation, basic format for a calendar date
and time character encoding of day. The text format is a concatenation inline binary data. For example, an inline
attachment of the "date",
followed by the LATIN CAPITAL LETTER T character (ASCII decimal 84)
time designator, followed by the "time" format defined below. an object code MAY BE included in an iCalendar object.

Formal Definition: The
data value type is defined by the following
notation:

date-time

binary = date "T" time ;As specified above in date and time

The following represents July 14, 1997, at 1:30 PM in UTC and the
equivalent time in New York (four hours behind UTC in DST), expressed
as a local time and local time with UTC offset:

19970714T133000Z
19970714T083000
19970714T083000-0400

4.1.10.5 Duration

The "DURATION" data type is used to identify properties that contain
a duration of time. The format is expressed *(4b-char) [b-end]
; A "B" encoded character string, as the [ISO 8601] basic
format for the duration of time. The format can represent durations
in terms of years, months, days, hours, minutes, and seconds. The
data type is defined by the following notation:

dur-second = 1*DIGIT "S"
dur-minute = 1*DIGIT "M" [dur-second]
dur-hour = 1*DIGIT "H" [dur-minute]
dur-time = "T" (dur-hour / dur-minute / dur-second)

dur-week = 1*DIGIT "W"
dur-day = 1*DIGIT "D"
dur-month = 1*DIGIT "M" [dur-day]
dur-year = 1*DIGIT "Y" [dur-month]
dur-date [RFC 2047].

b-end = (dur-day / dur-month (2b-char "==") / dur-year) [dur-time]

duration (3b-char "=")

b-char = (["+"] ALPHA / "-") "P" (dur-date DIGIT / dur-time "+" / dur-week)

For example, a duration "/"

Description: Property values with this value type MUST also include
the inline encoding parameter sequence of 10 years, 3 months, 15 days, 5 hours, 30
minutes and 20 seconds would be:

P10Y3M15DT5H30M20S

4.1.10.6 Float

The "FLOAT" ";ENCODING=B". That is, all
inline binary data MUST first be character encoded using the "B"
encoding method defined in [RFC 2047]. No additional content value
encoding (i.e., BACKSLASH character encoding) is defined for this
value type.

Example: The following is an abridged example of a "B" encoded binary
value data.

ATTACH;VALUE=BINARY:MIICajCCAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQA
wdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb
25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlvbiBTeXN0
<...remainder of "B" encoded binary data...>

4.3.2 Boolean

Value Name: BOOLEAN

Purpose: This value type is used to identify properties that contain
either a
real value number "true" or "false" boolean value. If the property permits, multiple "float"

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values MAY be specified using a COMMA character (ASCII decimal 44)
separator character.

Formal Definition: The data value type is defined defind by the following
notation:

float

boolean = (["+"] "TRUE" / "-") 1*DIGIT ["." 1*DIGIT] "FALSE"

Description: These values are case insensitive text. No additional
content value encoding (i.e., BACKSLASH character encoding) is
defined for this value type.

Example: For example:

1000000.0000001
1.333
-3.14

4.1.10.7 Integer

The "INTEGER" data example, any of the following are equivalent:

TRANSP;VALUE=BOOLEAN:TRUE
TRANSP;VALUE=BOOLEAN:true
TRANSP;VALUE=BOOLEAN:TrUe

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4.3.3 Calendar User Address

Value Name: CAL-ADDRESS

Purpose: This value type is used to identify properties that contain
a
signed integer value. calendar user address.

Formal Definition: The valid range for "integer" value type is -2147483648 to
2147483647. If as defined by the sign following
notation:

cal-address = uri

Description: The value is not specified, then a URI as defined by [RFC 1738] or any other
IANA registered form for a URI. When used to address an Internet
email transport address for a calendar user, the value MUST be a
MAILTO URI, as defined by [RFC 1738].No additional content value
encoding (i.e., BACKSLASH character encoding) is assumed defined for this
value type.

Example:

ATTENDEE;VALUE=CAL-ADDRESS:MAILTO:jane_doe@host.com

4.3.4 Date

Value Name: DATE

Purpose: This value type is used to be positive. identify values that contain a
calendar date.

Formal Definition: The value type is defined by the following
notation:

date = date-value *("," [WSP] date-value)

date-value = date-fullyear date-month date-mday
date-fullyear = 4DIGIT
date-month = 2DIGIT ;01-12
date-mday = 2DIGIT ;01-28, 01-29, 01-30, 01-31
;based on month/year

Description: If the property permits, multiple "integer" "date" values MAY be
specified using a COMMA character (ASCII decimal 44) separator
character. The data
character.The format for the value type is defined by expressed as the following notation:

integer = (["+"] / "-") *DIGIT

For example:

1234567890
-1234567890
+1234567890
432109876

4.1.10.8 Period of Time [ISO
8601] complete representation, basic format for a calendar date. The "PERIOD" data type is used to identify values that contain
textual format specifies a
precise period four-digit year, two-digit month, and two-
digit day of time. the month. There are two forms of a period of time.

A period of time MAY be identified by it's start no separator characters between the
year, month and it's end. This
format day component text.

No additional content value encoding (i.e., BACKSLASH character
encoding) is expressed as the [ISO 8601] complete representation, basic
format defined for "DATE-TIME" start of the period, followed by this value type.

Example: The following represents July 14, 1997:

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19970714

4.3.5 Date-Time

Value Name: DATE-TIME

Purpose: This value type is used to identify values that specify a SOLIDUS
character (ASCII decimal 47), followed by the "DATE-TIME" of the end
precise calendar data and time of day.

Formal Definition: The value type is defined by the period. For example, the period starting at 10 AM following
notation:

date-time = dt-value *("," [WSP] dt-value)

dt-value = date "T" time ;As specified above in Seattle
(eight hours behind UTC) on January 1, 1997 date and ending at 11 PM in
Seattle on January 1, 1997 would be:

19970101T100000-0800/19970101T230000-0800

A period of time

Description: If the property permits, multiple "date-time" values MAY also
be specified using a COMMA character (ASCII decimal 44) separator
character. No additional content value encoding (i.e., BACKSLASH
character encoding) is defined by for this value type.

The "DATE-TIME" data type is used to identify values that contain a start
precise calendar date and a duration time of
time. day. The format is expressed as based on the
[ISO 8601] complete representation, basic format for the "DATE-TIME" start a calendar date
and time of day. The text format is a concatenation of the period, "date",
followed by a SOLIDUS the LATIN CAPITAL LETTER T character (ASCII decimal 47), 84)
time designator, followed by the
[ISO 8601] basic format for "DURATION" of the period. For example,
the period start at 10 AM in Seattle (eight hours behind UTC) on
January 1, 1997 and lasting 5 hours and 30 minutes would be:

19970101T100000-0800/PT5H30M

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The "DATE-TIME" data type is defined by the following notation:

period-explicit = date-time "/" date-time
;ISO 8601 complete representation basic format for a period of expresses time
;consisting values in three forms:

The form of a start date and end. The start time with UTC offset MUST NOT be before used. For
example, the end.

period-start = date-time "/" duration
;ISO 8601 complete representation basic format following is not valid for a period of date-time value:

DTSTART:19980119T230000-0800

FORM #1: DATE WITH LOCAL TIME

The date with local time
;consisting of form is simply a start and duration date-time value that does
not contain the UTC designator nor does it reference a time zone. For
example, the following represents Janurary 18, 1998, at 11 PM:

DTSTART:19980118T230000

Date-time values of time.

period = period-explicit / period-start

4.1.10.9 Recurrence Rule

The "RECUR" data this type is are said to be "floating" and are not
bound to any time zone in particular. They are used to identify properties represent the
same hour, minute, and second value regardless of which time zone is
currently being observed. For example, an event MAY be defined that contain
indicates that an individual will be busy from 11:00 AM to 1:00 PM
every day, no matter which timezone the person is in. In these cases,
a
recurrence rule specification. local time MAY be specified. The data type is recipient of an iCalendar object
with a structured property value consisting of a list of one or more recurrence grammar components.
Each component is defined by a NAME=VALUE pair. The components are
separated from each other by local time, without any
relative time zone information, should interpret the SEMICOLON character (ASCII decimal
59). The components are not ordered value as being
fixed to whatever timezone the ATTENDEE is in at any particular sequence.
Individual components MAY only be specified once.

The FREQ component identifies the type of recurrence rule. given moment.
This
component MUST be specified means that two ATTENDEEs may participate in the recurrence rule. Valid values
include SECONDLY, to specify repeating events based on an interval of same event at

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different UTC times; floating time should only be used where that is
reasonable behavior.

In most cases, a second or more; MINUTELY, to specify repeating events based on an
interval of fixed time is desired. To properly communicate a minute or more; HOURLY, to specify repeating events
based on an interval of an hour or more; DAILY, to specify repeating
events based on an interval of
fixed time in a day property value, either UTC time or more; WEEKLY, to specify
repeating events based on an interval local time with
time zone reference MUST be specified.

The use of local time in a week or more; MONTHLY, DATE-TIME value without the TZID property
parameter is to
specify repeating events based on an interval of be interpreted as a month or more; and
YEARLY, to specify repeating events based on an interval local time value, regardless of a year or
more.

The INTERVAL component contains a positive integer representing how
often
the recurrence rule repeats. existence of "VTIMEZONE" calendar components in the iCalendar
object.

FORM #2: DATE WITH UTC TIME

The default value is "1" or every
minute for a MINUTELY rule, every hour for a HOURLY rule, every day
for a DAILY rule, every week for a WEEKLY rule, every month for a
MONTHLY rule and every year for a YEARLY rule.

The UNTIL component defines a date-time value which bounds the
recurrence rule in an inclusive manner. If the value specified by
UNTIL is synchronized date with the specified recurrence, this date-time
becomes the last instance of the recurrence. If not present, and the
COUNT component is also not present, the RRULE is considered to
repeat forever.

The COUNT component defines the number of occurrences at which to
range-bound the recurrence. This component is ignored if the "UNTIL"
component UTC time, or absolute time, is also present.

The BYSECOND component specifies identified by a COMMA LATIN
CAPITAL LETTER Z suffix character (ASCII decimal 44)
separated list of seconds within a minute. Valid values are 0 to 60.

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Zero is the beginning of 90), the minute and 60 is UTC
designator, appended to the beginning of time value. For example, the
next minute. following
represents January 19, 1998, at 0700 UTC:

DTSTART:19980119T070000Z

The BYMINUTE component specifies a COMMA character (ASCII decimal 44)
separated list of minutes within an hour. Valid TZID property parameter MUST NOT be applied to DATE-TIME
properties whose time values are 0 specified in UTC.

FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE

The date and local time with reference to 60.
Zero time zone information is
identified by the beginning of use the hour and 60 TZID property parameter to reference the
appropriate time zone definition. TZID is discussed in detail in the beginning of
section on Time Zone. For example, the next
hour. following represents 2 AM in
New York on Janurary 19, 1998:

DTSTART;TZID=America-New_York:19980119T020000

Example: The BYHOUR component specifies a COMMA character (ASCII decimal 44)
separated list of hours following represents July 14, 1997, at 1:30 PM in New
York City in each of the day. Valid values are 0 to 24. Zero is
the start of three time formats, using the day "DTSTART"
property.

DTSTART:19970714T133000 ;Local time
DTSTART:19970714T153000Z ;UTC time
DTSTART;TZID=America-NYC:19970714T133000 ;Local time and 24 time
; zone reference

4.3.6 Duration

Value Name: DURATION

Purpose: This value type is the start used to identify properties that contain
a duration of the next day. time.

Formal Definition: The BYDAY component specifies value type is defined by the following
notation:

duration = dur-value *("," [WSP] dur-value)

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dur-value = (["+"] / "-") "P" (dur-date / dur-time / dur-week)

dur-date = (dur-day) [dur-time]
dur-time = "T" (dur-hour / dur-minute / dur-second)
dur-week = 1*DIGIT "W"

dur-hour = 1*DIGIT "H" [dur-minute]
dur-minute = 1*DIGIT "M" [dur-second]
dur-second = 1*DIGIT "S"
dur-day = 1*DIGIT "D"

Description: If the property permits, multiple "duration" values MAY
be specified using a COMMA character (ASCII decimal 44)
separated list separator
character.The format is expressed as the [ISO 8601] basic format for
the duration of days time. The format can represent durations in terms of the week; MO, indicates Monday; TU,
indicates Tuesday; WE, indicates Wednesday; TH, indicates Thursday;
FR, indicates Friday; SA, indicates Saturday; SU, indicates Sunday.

Each BYDAY
years, months, days, hours, minutes, and seconds.

No additional content value MAY also be preceded by a positive (+n) or negative
(-n) integer. If present, encoding (i.e., BACKSLASH character
encoding) are defined for this indicates the nth occurrence value type.

Example: A duration of the
specific day within the MONTHLY or YEARLY RRULE. For example, within
a MONTHLY rule, +1MO (or simply 1MO) represents the first Monday
within the month, whereas -1MO represents the last Monday 15 days, 5 hours, 30 minutes and 20 seconds
would be:

P15DT5H30M20S

A duration of the
month. If an integer modifier 7 weeks would be:

P15DT5H30M20S

4.3.7 Float

Value Name: FLOAT

Purpose: This value type is not present, it means all days of
this used to identify properties that contain
a real value number value.

Formal Definition: The value type within is defined by the specified frequency. For example, within a
MONTHLY rule, MO represents all Mondays within following
notation:

float = float-value *("," [WSP] float-value)

float-value = (["+"] / "-") 1*DIGIT ["." 1*DIGIT]

Description: If the month.

The BYMONTHDAY component specifies property permits, multiple "float" values MAY be
specified using a COMMA character (ASCII decimal 44) separated list of days of the month. Valid values are 1 to 31 or
-31 separator
character.

No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.

Example:

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1000000.0000001
1.333
-3.14

4.3.8 Integer

Value Name:INTEGER

Purpose: This value type is used to -1.

Each BYMONTHDAY identify properties that contain
a signed integer value.

Formal Definition: The value type is defined by the following
notation:

integer = integer-value *("," [WSP] integer-value)

integer-value = (["+"] / "-") *DIGIT

Description: If the property permits, multiple "integer" values MAY include
be specified using a postive (+n) or negative (-n)
integer. COMMA character (ASCII decimal 44) separator
character.The valid range for "integer" is -2147483648 to 2147483647.
If present, this indicates the nth occurrence of the
specific day of the month within the MONTHLY rule. If an integer
modifier sign is not present, it means all days of this type within the
specified frequency. For example, within a MONTHLY rule, -10
represents specified, then the tenth value is assumed to be
positive. If the last day of the month.

The BYYEARDAY component specifies property permits, multiple "integer" values MAY be
specified using a COMMA character (ASCII decimal 44) separated list of days separator
character.

No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.

Example:

1234567890
-1234567890
+1234567890
432109876

4.3.9 Period of the year. Valid values are 1 to 366 or
-366 Time

Value Name: PERIOD

Purpose: This value type is used to -1. For example, -1 represents the last day identify values that contain a
precise period of time.

Formal Definition: The data type is defined by the year
(December 31st). following
notation:

period = period-value *("," [WSP] period-value)

period-value = period-explicit / period-start

period-explicit = date-time "/" date-time
;ISO 8601 complete representation basic format for a period of time
;consisting of a start and end. The BYWEEKNO component specifies start MUST be before the end.

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period-start = date-time "/" duration
;ISO 8601 complete representation basic format for a comma-separated list period of weeks time
;consisting of a start and duration of time.

Description: If the year. Valid property permits, multiple "period" values MAY be
specified using a COMMA character (ASCII decimal 44) separator
character. There are 1 to 53. This corresponds to weeks
according to week numbering as defined in [ISO 8601]. That is, two forms of a week
as "A seven day period within a calendar year, starting on a Monday
and of time. A period of time
MAY be identified by its ordinal number within the year; the first
calendar week of the year is the one that includes the first Thursday
of that year." it's start and it's end. This component format is only valid
expressed as the [ISO 8601] complete representation, basic format for YEARLY rules.

Each BYWEEKNO value MAY include
"DATE-TIME" start of the period, followed by a positive (+n) or negative (-n)
integer. If present, this indicates SOLIDUS character
(ASCII decimal 47), followed by the nth occurrence "DATE-TIME" of the
specific week end of the year within the YEARLY rule. If an integer
modifier is not present, it means all days
period. A period of this type within the

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specified frequency. For example, within also be defined by a YEARLY rule, 3 represents
the third week of the year.

The BYMONTH component specifies start and a comma separated list of months
duration of
the year. Valid values are 1 to 12. time. The WKST component specifies format is expressed as the day on which [ISO 8601] complete
representation, basic format for the workweek starts.
Valid values are MO, TU, WE, TH, FR, SA and SU. This is significant
when a WEEKLY RRULE has an interval greater than 1, and a BYDAY
component is specified. The default value is MO.

The BYSETPOS component specifies "DATE-TIME" start of the period,
followed by a COMMA SOLIDUS character (ASCII decimal 44)
separated list of values which corresponds to the nth occurrence
within 47), followed by the set
[ISO 8601] basic format for "DURATION" of events specified by the rule. Valid values are 1 to
366 or -366 to -1. It MUST only be used in conjunction with another
Byxxx component. For example "the last work day of the month" could
be represented as:

RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1

Each BYSETPOS value MAY include a positive (+n) or negative (-n)
integer. If present, this indicates the nth occurrence of the
specific occurrence within the set of events specified by the rule.

If BYxxx component values are found which are beyond the available
scope (ie, BYMONTHDAY=30 in February), they are simply ignored.

Information, not contained in the rule, necessary to determine the
various recurrence instance period.

Example: The period starting at 18:00:00 UTC, on January 1, 1997 and
ending at 07:00:00 UTC on January 2, 1997 would be:

19970101T180000Z/19970102T070000Z

The period start time at 18:00:00 on January 1, 1997 and dates are derived from the
Start Time (DTSTART) entry attribute. For example,
"FREQ=YEARLY;BYMONTH=1" doesn't specify a specific day within the
month or a time. This information lasting 5 hours
and 30 minutes would be the same as what be:

19970101T180000Z/PT5H30M

No additional content value encoding (i.e., BACKSLASH character
encoding) is
specified for DTSTART.

BYxxx components modify the recurrence in some manner. BYxxx
components defined for a period of time which is the same or greater than the
frequency generally reduce or limit the number of occurrences of the
recurrence generated. For example, "FREQ=DAILY;BYMONTH=1" reduces the
number of recurrence instances from all days (if BYMONTH tag this value type.

4.3.10 Recurrence Rule

Value Name: RECURR

Purpose: This value type is not
present) used to all days in January. BYxxx components for identify properties that contain
a period of
time less than recurrence rule specification.

Formal Definition: The value type is defined by the frequency generally increase or expand the number
of occurrences of the recurrence. For example,
"FREQ=YEARLY;BYMONTH=1,2" increases the number of days within the
yearly recurrence set from 1 (if BYMONTH tag is not present) to 2.

If only one BYxxx component is specified in the recurrence rule, the
list of "n" unique values would cause "n" occurrences of the
recurrence within each specified frequency interval, where each
unique list value is substituted in the appropriate date position
within DTSTART for each such occurrence.

If multiple BYxxx components are specified, then the list of "n"
unique values for each lower frequency BYxxx components is applied to
the list of "n" unique values for higher frequency BYxxx components. following
notation:

recur = recur-value *("," [WSP] recur-value)

recur-value = "FREQ"=freq ";"
[("UNTIL" "=" enddate ";") / ("COUNT" "=" 1*DIGIT ";")]
["INTERVAL" "=" 1*DIGIT ";"]
["BYSECOND" "=" byseclist ";"]
["BYMINUTE" "=" byminlist ";"]
["BYHOUR" "=" byhrlist ";"]
["BYDAY" "=" bywdaylist ";"]
["BYMONTHDAY" "=" bymodaylist ";"]
["BYYEARDAY" "=" byyrdaylist ";"]
["BYWEEKNO" "=" bywknolist ";"]
["BYMONTH" "=" bymolist ";"]
["BYSETPOS" "=" bysplist ";"]

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This process will not always increase the set of occurrences. If a
higher component is inconsistent with what was generated for lower
components, it would reduce the set. The ordering of BYxxx components
from lower frequency to higher frequency is as follows: BYMINUTE,
BYHOUR, BYDAY, BYMONTHDAY, BYYEARDAY, BYWEEKNO, BYMONTH, BYSETPOS.

Here is an example of evaluating multiple BYxxx components.

"FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=SU;BYHOUR=8,9;BYMINUTE=30"

would first apply the "BYMINUTE=30" To "BYHOUR=8,9" to arrive at
"every 8:30AM and 9:30AM". This in turn would be applied to
"BYDAY=SU" to arrive at "every Sunday at 8:30AM and 9:30AM". This
would be applied to "BYMONTH=1" to arrive at "every Sunday in January
at 8:30AM and 9:30AM". Considering the FREQUENCY and INTERVAL, this
would become "Every Sunday in January at 8:30AM and 9:30AM, every
other year". If the BYMINUTE, BYDAY, BYMONTHDAY, BYYEARDAY, BYHOUR or
BYMONTH component was missing, the appropriate mintues, hour, day or
month would have been retrieved from DTSTART.

The data type is defined by the following notation:

recur = "FREQ"=freq ";"
[("UNTIL" "=" enddate ";") / ("COUNT" "=" 1*DIGIT ";")]
["INTERVAL" "=" 1*DIGIT ";"]
["BYSECOND" "=" byseclist ";"]
["BYMINUTE" "=" byminlist ";"]
["BYHOUR" "=" byhrlist ";"]
["BYDAY" "=" bywdaylist ";"]
["BYMONTHDAY" "=" bymodaylist ";"]
["BYYEARDAY" "=" byyrdaylist ";"]
["BYWEEKNO" "=" bywknolist ";"]
["BYMONTH" "=" bymolist ";"]
["BYSETPOS" "=" bysplist ";"]
["WKST" "=" weekday ";")]
*("X-" word "=" word) ";"
;Individual March 6, 1998

["WKST" "=" weekday ";")]
*(x-name "=" text) ";"
;Individual components MAY only be specified once.
;Rule components need not be specified in particular any order.

freq = "SECONDLY" / "MINUTELY" / "HOURLY" / "DAILY"
/ "WEEKLY" / "MONTHLY" / "YEARLY"

enddate = date
enddate =/ date-time ;A UTC value

byseclist = seconds / ( seconds *("," seconds) )

seconds = 1DIGIT / 2DIGIT ;0 to 60 59

byminlist = minutes / ( minutes *("," minutes) )

minutes = 1DIGIT / 2DIGIT ;0 to 60 59

byhrlist = hour / ( hour *("," hour) )

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hour = 1DIGIT / 2DIGIT ;0 to 24 23

bywdaylist = weekdaynum / ( weekdaynum *("," weekdaynum) )

weekdaynum = [([plus] ordwk / minus ordwk)] weekday

plus = "+"

minus = "-"

ordwk = 1DIGIT / 2DIGIT ;1 to 53

weekday = "SU" / "MO" / "TU" / "WE" / "TH" / "FR" / "SA"
;Corresponding to SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY,
;FRIDAY, SATURDAY and SUNDAY days of the week.

bymodaylist = monthdaynum / ( monthdaynum *("," monthdaynum) )

monthdaynum = ([plus] ordmoday) / (minus ordmoday)

ordmoday = 1DIGIT / 2DIGIT ;1 to 31

byyrdaylist = yeardaynum / ( yeardaynum *("," yeardaynum) )

yeardaynum = ([plus] ordyrday) / (minus ordyrday)

ordyrday = 1DIGIT / 2DIGIT / 3DIGIT ;1 to 366

bywknolist = weeknum / ( weeknum *("," weeknum) )

weeknum = ([plus] ordwk) / (minus ordwk)

bymolist = monthnum / ( monthnum *("," monthnum) )

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monthnum = 1DIGIT / 2DIGIT ;1 to 12

bysplist = setposday / ( setposday *("," setposday) )

setposday = yeardaynum

For example,

Description: If the following is a rule which specifies 10 meetings
which occur every other day:

FREQ=DAILY;COUNT=10;INTERVAL=2

There are other examples property permits, multiple "recur" values MAY be
specified in the "RRULE" specification.

4.1.10.10 Text using a COMMA character (ASCII decimal 44) separator
character. The "TEXT" data value type is used to identify values that contain human
readable text. The character set and language in which the text is
represented a structured value consisting of a list
of one or more recurrence grammar components. Each component is controlled
defined by the "LANGUAGE" property parameters. a NAME=VALUE pair. The
data type is defined components are separated from each
other by the ABNF for "text" SEMICOLON character (ASCII decimal 59). The components
are not ordered in section 4.1.1.

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4.1.10.11 Time
only be specified once.

The "TIME" data FREQ component identifies the type is used to identify of recurrence rule. This
component MUST be specified in the recurrence rule. Valid values that contain
include SECONDLY, to specify repeating events based on an interval of
a time second or more; MINUTELY, to specify repeating events based on an
interval of day. The format is expressed as the [ISO 8601] complete
representation, basic format for a time minute or more; HOURLY, to specify repeating events
based on an interval of day. The text format
consists an hour or more; DAILY, to specify repeating
events based on an interval of a two-digit 24-hour of the day (i.e., values 0-23), two-
digit minute in the hour (i.e., values 0-59), and two-digit seconds
in the minute (i.e., values 0-59). If seconds or more; WEEKLY, to specify
repeating events based on an interval of the minute are not
supported by a week or more; MONTHLY, to
specify repeating events based on an implementation, then interval of a value month or more; and
YEARLY, to specify repeating events based on an interval of "00" should be
specified for a year or
more.

The INTERVAL component contains a positive integer representing how
often the seconds component. Fractions of an hour, minute recurrence rule repeats. The default value is "1" or
second are not supported every
minute for a MINUTELY rule, every hour for a HOURLY rule, every day
for a DAILY rule, every week for a WEEKLY rule, every month for a
MONTHLY rule and every year for a YEARLY rule.

The UNTIL component defines a date-time value which bounds the
recurrence rule in an inclusive manner. If the value specified by this format. This format
UNTIL is used to
represent local time, local time synchronized with UTC offset the specified recurrence, this date-time
becomes the last instance of the recurrence. If not present, and UTC time. UTC
time the
COUNT component is identified by a LATIN CAPITAL LETTER Z suffix character
(ASCII decimal 90), also not present, the UTC designator, appended RRULE is considered to the time.
repeat forever.

The
local time with UTC offset is expressed as a local time, suffixed
with COUNT component defines the signed offset from UTC. The UTC offset number of occurrences at which to
range-bound the recurrence. This component is express as ignored if the 2-
digit hours and 2-digit minutes difference from UTC. It "UNTIL"
component is expressed
as positive, with also present.

The BYSECOND component specifies a leading PLUS SIGN COMMA character (ASCII decimal 43),
if the local time is ahead 44)
separated list of UTC. It is expressed as seconds within a negative,
with minute. Valid values are 0 to 59.
The BYMINUTE component specifies a leading HYPEN-MINUS COMMA character (ASCII decimal 45), if the local
time is behind UTC. Local time has neither the UTC designator nor the
UTC offset suffix text. 44)
separated list of minutes within an hour. Valid values are 0 to 59.
The data type is defined by the following
notation:

time-hour = 2DIGIT ;00-23
time-minute = 2DIGIT ;00-59
time-second = 2DIGIT ;00-60
;The "60" value is used to account for years with "leap" seconds.
time-numzone = ("+" / "-") time-hour time-minute
time-zone = "Z" / time-numzone

time = time-hour time-minute time-second [time-zone]

For example, the following represents 8:30 AM in New York, five BYHOUR component specifies a COMMA character (ASCII decimal 44)
separated list of hours
behind UTC, in local time and local time with UTC offset. In
addition, 1:30 PM in UTC is illustrated:

083000
083000-0500
133000Z

There of the day. Valid values are cases when a floating time is intended within a property
value. For example, an event MAY be defined that indicates that an
individual will be busy from 11:00 AM 0 to 1:00 PM every day. In these
cases, a local time MAY be specified. 23.

The recipient of an iCalendar
object with BYDAY component specifies a property value consisting COMMA character (ASCII decimal 44)
separated list of days of a local time, without any
relative time zone information, should interpret the value as being
fixed to the recipient's locale and time zone. In most cases, a fixed
time is desired. To properly communicate a fixed time in a property
value, either UTC, local time with UTC offset, or local time with a
"VTIMEZONE" calendar component MUST be specified. week; MO, indicates Monday; TU,

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4.1.10.12 URI

The "URI" data type is used to identify values that contain March 6, 1998

indicates Tuesday; WE, indicates Wednesday; TH, indicates Thursday;
FR, indicates Friday; SA, indicates Saturday; SU, indicates Sunday.

Each BYDAY value MAY also be preceded by a uniform
resource identifier (URI) type of reference to the property value.
This data type might be used to reference binary information, for
values that are large, positive (+n) or otherwise undesirable to include directly
in negative
(-n) integer. If present, this indicates the iCalendar object.

The URI value formats in RFC 1738, RFC 2111 and any other IETF
registered value format MAY be specified.

The data type is defined by nth occurrence of the following notation:

uri = <As defined by any IETF RFC>

Any IANA registered URI format MAY be used. These include, but are
not limited to, those defined in RFC 1738 and RFC 2111.
specific day within the MONTHLY or YEARLY RRULE. For example, the following is a URI for within
a network file:

http://host1.com/my-report.txt

4.1.10.13 UTC Offset

The "UTC-OFFSET" data type is used to identify properties that
contain MONTHLY rule, +1MO (or simply 1MO) represents the first Monday
within the month, whereas -1MO represents the last Monday of the
month. If an offset from UTC to local time. The data type integer modifier is defined by
the following notation:

utc-offset = time-numzone ;As defined above in time data not present, it means all days of
this type

The PLUS SIGN character MUST be within the specified for positive UTC offsets. frequency. For example, within a
MONTHLY rule, MO represents all Mondays within the following are UTC offsets are given for standard
time for New York (five hours behind UTC) and Geneva (one hour ahead
of UTC):

-0500

+0100

4.2 iCalendar object month.

The Calendaring and Scheduling Core Object is BYMONTHDAY component specifies a collection COMMA character (ASCII decimal
44) separated list of
calendaring and scheduling information. Typically, this information
will consist of a single iCalendar object. However, multiple
iCalendar objects MAY be sequentially, grouped together. The first
line and last line days of the iCalendar object MUST contain a pair of
iCalendar object delimiter strings. The syntax for an iCalendar
object is as follows:

icalobject = "BEGIN" ":" [WSP] "VCALENDAR" CRLF
icalbody
"END" ":" [WSP] "VCALENDAR" CRLF [icalobject]

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Internet Draft C&S Core Object Specification November 14, 1997

The following is include a simple example positive (+n) or negative (-n)
integer. If present, this indicates the nth occurrence of an iCalendar object:

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
BEGIN:VEVENT
DTSTART:19970714T120000-0500
DTEND:19970714T235959-0500
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR

4.3 Property

A property is the definition
specific day of an individual attribute describing a
calendar property or a calendar component. A property takes the form
defined by month within the "contentline" notation defined in section 4.1.1.

The following is MONTHLY rule. If an example of a property:

DTSTART:19960415T083000-05:00

This memo places no imposed ordering integer
modifier is not present, it means all days of properties this type within an
iCalendar object.

Property names, parameter names and parameter values (i.e.,
everything the
specified frequency. For example, within a MONTHLY rule, -10
represents the tenth to the left last day of the ":" on month.

The BYYEARDAY component specifies a line) COMMA character (ASCII decimal
44) separated list of days of the year. Valid values are case insensitive. 1 to 366 or
-366 to -1. For example, -1 represents the property name "DUE" is the same as "due" and "Due".

4.4 Calendar Components

The body last day of the iCalendar object consists of year
(December 31st).

The BYWEEKNO component specifies a sequence comma-separated list of calendar
properties and one or more calendar components. The calendar
properties weeks of
the year. Valid values are attributes that apply 1 to the calendar 53. This corresponds to weeks
according to week numbering as defined in [ISO 8601]. That is, a whole. The
calendar components are collections of properties that with week
as "A seven day period within a
particular calendar semantic. For example, year, starting on a Monday
and identified by its ordinal number within the year; the first
calendar week of the year is the one that includes the first Thursday
of that year." This component is only valid for YEARLY rules.

Each BYWEEKNO value MAY
specify a an event, include a to-do, journal entry, time zone information, or
free/busy time information, positive (+n) or alarm.

The body negative (-n)
integer. If present, this indicates the nth occurrence of the iCalenar Object is defined by
specific week of the following notation:

icalbody = calprops 1*component

calprops = [calscale] prodid method [source] [name] version

component = 1*(eventc / todoc / journalc / freebusyc /
/ timezonec)

4.4.1 Event Component

A "VEVENT" calendar component year within the YEARLY rule. If an integer
modifier is not present, it means all days of this type within the
specified frequency. For example, within a grouping YEARLY rule, 3 represents
the third week of the year.

The BYMONTH component properties
and an OPTIONAL "VALARM" calendar component that represent specifies a
scheduled amount comma separated list of time months of
the year. Valid values are 1 to 12.

The WKST component specifies the day on a calendar. For example, it MAY be which the workweek starts.
Valid values are MO, TU, WE, TH, FR, SA and SU. This is significant
when a WEEKLY RRULE has an
activity; such as interval greater than 1, and a one-hour, department meeting from 8:00 AM BYDAY
component is specified. The default value is MO.

The BYSETPOS component specifies a COMMA character (ASCII decimal 44)
separated list of values which corresponds to the nth occurrence
within the set of events specified by the rule. Valid values are 1 to 9:00

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AM, tomorrow. Generally, these events will take up time on an
individual calendar. Hence, the event will appear as an opaque
interval March 6, 1998

366 or -366 to -1. It MUST only be used in a search for busy time. Alternately, conjunction with another
Byxxx component. For example "the last work day of the event month" could
be represented as:

RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1

Each BYSETPOS value MAY have
its Time Transparency include a positive (+n) or negative (-n)
integer. If present, this indicates the nth occurrence of the
specific occurrence within the set to "TRANSPARENT" in order to prevent
blocking of events specified by the event rule.

If BYxxx component values are found which are beyond the available
scope (ie, BYMONTHDAY=30 in February), they are simply ignored.

Information, not contained in searches for busy time.

The "VEVENT" is also the calendar component used rule, necessary to specify an
anniversary or daily reminder within a calendar. These events have a
DATE value type for determine the "DTSTART"
various recurrence instance start time and "DTEND" properties instead of dates are derived from the default data type of DATE-TIME. If such
Start Time (DTSTART) entry attribute. For example,
"FREQ=YEARLY;BYMONTH=1" doesn't specify a "VEVENT" has an end
time, it MUST specific day within the
month or a time. This information would be specified the same as a DATE value also. The anniversary type
of "VEVENT" MAY span more than one date (i.e, "DTEND" property value what is set to a calendar date after
specified for DTSTART.

BYxxx components modify the "DTSTART" property value).

The "DTSTART" property recurrence in some manner. BYxxx
components for a "VEVENT" specifies period of time which is the inclusive start same or greater than the
frequency generally reduce or limit the number of occurrences of the event.
recurrence generated. For recurring events, it also specifies the very first
instance in example, "FREQ=DAILY;BYMONTH=1" reduces the
number of recurrence set. The "DTEND" property instances from all days (if BYMONTH tag is not
present) to all days in January. BYxxx components for a "VEVENT"
calendar component specifies the non-inclusive end period of
time less than the event. For
cases where a "VEVENT" calendar component specifies a "DTSTART"
property with a DATE data type but no "DTEND" property, the events
non-inclusive end is frequency generally increase or expand the end number
of occurrences of the calendar date specified by the
"DTSTART" property. recurrence. For cases where a "VEVENT" calendar component
specifies a "DTSTART" property with a DATE-TIME data type but no
"DTEND" property, the event ends on example,
"FREQ=YEARLY;BYMONTH=1,2" increases the same calendar date and time number of day specified by days within the "DTSTART" property.

A "VEVENT" calendar
yearly recurrence set from 1 (if BYMONTH tag is not present) to 2.

If only one BYxxx component is defined by specified in the following notation:

eventc = "BEGIN" ":" [WSP] "VEVENT" CRLF
eventprop *alarmc
"END" ":" [WSP] "VEVENT" CRLF

eventprop = *attach *attendee *categories [class] *comment
*contact [created] [description] [dtend / duration]
dtstart *exdate *exrule [geo] [last-mod] [location]
[priority] [rstatus] [related] *resources *rdate
*rrule dtstamp [seq] [status] summary [transp] uid
[url] [recurid]

The "VEVENT" calendar component cannot be nested recurrence rule, the
list of "n" unique values would cause "n" occurrences of the
recurrence within another
calendar component. The "VEVENT" calendar components MAY be related
to each other or specified frequency interval, where each
unique list value is substituted in the appropriate date position
within DTSTART for each such occurrence.

If multiple BYxxx components are specified, then after evaluating the
specified FREQ and INTERVAL components, the BYxxx components are
applied to a "VTODO" or "VJOURNAL" calendar component with the "RELATED-TO" property.

The current set of evaluated occurrences in the following
order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY, BYDAY, BYHOUR,
BYMINUTE, BYSECOND and BYSETPOS.

Here is an example of evaluating multiple BYxxx components.

DTSTART;TZID=EST=19970105T083000
RRULE:FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=SU;BYHOUR=8,9;
BYMINUTE=30

First, the "VEVENT" calendar component used "INTERVAL=2" would be applied to represent a meeting that will also "FREQ=YEARLY" to arrive
at "every other year". Then, "BYMONTH=1" would be opaque applied to searches for busy
time:

BEGIN:VEVENT
UID:19970901T130000Z-123401@host.com
DTSTAMP:19970901T1300Z
DTSTART:19970903T083000-0800
DTEND:19970903T110000-0800
SUMMARY:Annual Employee Review arrive
at "every January, every other year". Then, "BYDAY=SU" would be
applied to arrive at "every Sunday in January, every other year".
Then, "BYHOUR=8,9" would be applied to arrive at "every Sunday in

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CLASS:PRIVATE
CATEGORIES:BUSINESS,HUMAN RESOURCES
END:VEVENT

The following is an example of the "VEVENT" calendar component used
to represent a reminder that will not be opaque, but rather
transparent, March 6, 1998

January at 8 AM and 9 AM, every other year". Then, "BYMINUTE=30"
would be applied to searches for busy time:

BEGIN:VEVENT
UID:19970901T130000Z-123402@host.com
DTSTAMP:19970901T1300Z DTSTART:19970401T083000-0800
DTEND:19970401T170000-0800
SUMMARY:Laurel is arrive at "every Sunday in sensitivity awareness class.
CLASS:PUBLIC
CATEGORIES:BUSINESS,HUMAN RESOURCES
TRANSP:TRANSPARENT
END:VEVENT January at 8:30 AM and
9:30 AM, every other year". Similarly, if the BYMINUTE, BYHOUR,
BYDAY, BYMONTHDAY or BYMONTH component were missing, the appropriate
minute, hour, day or month would have been retrieved from the
"DTSTART" property.

No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.

Example: The following is an example of the "VEVENT" calendar component used
to represent an anniversary that will a rule which specifies 10 meetings which
occur annually. Since it takes
up no time, it will not appear as opaque every other day:

FREQ=DAILY;COUNT=10;INTERVAL=2

There are other examples specified in a search for busy time;
no matter what the "RRULE" specification.

4.3.11 Text

Value Name: TEXT

Purpose This value of the "TRANSP" property indicates:

BEGIN:VEVENT
UID:19970901T130000Z-123403@host.com
DTSTAMP:19970901T1300Z
DTSTART:19971102
SUMMARY:Our Blissful Anniversary
CLASS:CONFIDENTIAL
CATEGORIES:ANNIVERSARY,PERSONAL,SPECIAL OCCASION
RRULE:FREQ=YEARLY
END:VEVENT

4.4.2 To-do Component

A "VTODO" calendar component type is a grouping of component properties
and an OPTIONAL "VALARM" calendar component that represent an action-
item or assignment. For example, it MAY be an item of work assigned used to an individual; such as "turn in travel expense today".

A "VTODO" calendar component identify values that contain human
readable text.

Formal Definition: The value type is defined by the following
notation:

todoc

text = "BEGIN" ":" [WSP] "VTODO" CRLF
todoprop *alarmc
"END" text-value *("," text-value)
; Folded according to folded-value syntax above or
; encoded according to param-value syntax above.

text-value = *(SAFE-CHAR / ":" [WSP] "VTODO" CRLF

todoprop / DQUOTE / ESCAPED-CHAR)

ESCAPED-CHAR = *attach *attendee *categories [class] *comment
[completed] *contact [created] [description] dtstamp
dtstart [due "\\" / duration] *exdate *exrule [geo]
[last-mod] [location] [percent] priority [rstatus]
[related] *resources *rdate *rrule [recurid] [seq]
[status] summary uid [url] "\;" / "\," / "\N" / "\n")
; \\ encodes \, \N or \n encodes newline
; \; encodes ;, \, encodes ,

NON-ASCII = %x80-FF
; use restricted by charset parameter
; on outer MIME object

SAFE-CHAR = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B
%x5D-7E / NON-ASCII
; Any character except CTLs, DQUOTE, ";", ":", "\", ","

Description: If the property permits, multiple "text" values MAY be
specified using a COMMA character (ASCII decimal 44) separator
character. The character set and language in which the text is
represented is controlled by the "LANGUAGE" property parameters.

An intentional formatted text line break MAY only be included in a
"TEXT" property value by representing the line break with the
character sequence of BACKSLASH (ASCII decimal 92), followed by a

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The "VTODO" calendar component cannot be nested within another
calendar component. If "VTODO" calendar components need to be related
to each other March 6, 1998

LATIN SMALL LETTER N (ASCII decimal 110) or a LATIN CAPITAL LETTER N
(ASCII decimal 78), that is "\n" or "\N".

The "TEXT" property values may also contain special characters that
are used to signify delimiters, such as a "VTODO" COMMA character for lists
of values or "VJOURNAL" calendar component, they
can specify a relationship with SEMICOLON character for structured values. In order to
support the "RELATED-TO" property.

The following is an example inclusion of a "VTODO" calendar component:

BEGIN:VTODO
UID:19970901T130000Z-123404@host.com
DTSTAMP:19970901T1300Z
DTSTART:19970415T083000-0500
DUE:19970415T235959-0500
SUMMARY:1996 Income Tax Preparation
CLASS:CONFIDENTIAL
CATEGORIES:FAMILY,FINANCE
PRIORITY:1
STATUS:NEEDS-ACTION
END:VEVENT

4.4.3 Journal Component

A "VJOURNAL" calendar component is a grouping of component properties
that represent one or more descriptive text notes on a particular
calendar date. The "DTSTART" these special characters in "TEXT" property is used
values, they need to specify the calendar
date that the journal entry is associated with. Generally, it will
have be escaped with a DATE BACKSLASH character. A
BACKSLASH character (ASCII decimal 92) in a "TEXT" property value data type, but it MAY also
MUST be used to specify escaped with another BACKSLASH character. A COMMA character
in a
DATE-TIME "TEXT" property value data type. Examples of a journal entry include a
daily record of MUST be escaped with a legislative body or BACKSLASH character
(ASCII decimal 92). A SEMICOLON character in a journal entry of individual
telephone contacts for the day or an ordered list of accomplishments
for the day. The calendar component can also "TEXT" property value
MUST be used to associate a
document escaped with a calendar date.

The "VJOURNAL" calendar component does not take up time on a
calendar. Hence, it does not play BACKSLASH character (ASCII decimal 92).
However, a role COLON character in free or busy time
searches a "TEXT" property value SHALL NOT be
escaped with a BACKSLASH character.Example: A multiple line value of:

Project XYZ Final Review
Conference Room - 3B
Come Prepared.

would be represented as:

Project XYZ Final Review\n Conference Room - it 3B\nCome Prepared.

4.3.12 Time

Value Name: TIME

Purpose: This value type is as though it has used to identify values that contain a
time transparency value of
TRANSPARENT. It is transparent to any such searches.

A "VJOURNAL" calendar component day.

Formal Definition: The data type is defined by the following
notation:

journalc

time = "BEGIN" ":" [WSP] "VJOURNAL" CRLF
jourprop
"END" ":" time-value *("," [WSP] "VJOURNAL" CRLF

jourprop time-value)

time-value = *attach *attendee *categories [class] *comment
*contact [created] [description] dtstart dtstamp
*exdate *exrule [last-mod] [related] *rdate *rrule
[rstatus] [seq] summary uid [url] [recurid]

The "VJOURNAL" calendar component cannot be nested within another
calendar component. If "VJOURNAL" calendar components need to be
related to each other or time-hour time-minute time-second [time-utc]

time-hour = 2DIGIT ;00-23
time-minute = 2DIGIT ;00-59
time-second = 2DIGIT ;00-60
;The "60" value is used to a "VEVENT" or "VTODO" calendar component,
they can specify a relationship account for years with "leap" seconds.

time-utc = "Z"

Description: If the "RELATED-TO" property. property permits, multiple "time" values MAY be
specified using a COMMA character (ASCII decimal 44) separator
character. No additional content value encoding (i.e., BACKSLASH
character encoding) is defined for this value type.

The following "TIME" data type is an example used to identify values that contain a time
of day. The format is based on the "VJOURNAL" calendar component: [ISO 8601] complete

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representation, basic format for this project. Lisa will escalate to
management. Next meeting on Tuesday.
2. Telephone Conference: ABC Corp. sales representative called
to discuss new printer. Promised to get us a demo by Friday.
3. Henry Miller (Handsoff Insurance): Car was totaled by tree.
Is looking into a loaner car. 654-2323 (tel).
END:VJOURNAL

4.4.4 Free/Busy Component

A "VFREEBUSY" calendar component is a grouping time of day. The text format
consists of component
properties that represents either a request for, or two-digit 24-hour of the day (i.e., values 0-23), two-
digit minute in the hour (i.e., values 0-59), and two-digit seconds
in the minute (i.e., values 0-59). Fractions of a reply with,
free or busy time information. Typically, second are not
supported by this component exists in an
iCalendar object that is being used format.

In parallel to either request or return free
or busy the "DATE-TIME" definition above, the "TIME" data type
expresses time information.

A "VFREEBUSY" calendar component is defined by values in three forms:

Note: The form of time with UTC offset MUST NOT be used. For example,
the following
notation:

freebusyc = "BEGIN" ":" [WSP] "VFREEBUSY" CRLF
fbprop
"END" ":" [WSP] "VFREEBUSY" CRLF

fbprop = fbrequest / fbreply

fbrequest = 1*attendee dtstart dtend [duration] *comment dtstamp
[last-mod] *related [seq] uid
;This set of properties is used NOT VALID for free/busy a time request.

fbreply = 1*attendee [created] *comment [dtstart dtend] dtstamp
*freebusy [last-mod] [related] [rstatus] [seq] uid
[url]
;This set of properties value:

230000-0800

FORM #1 LOCAL TIME

The local time form is used for free/busy simply a time reply.

The "VFREEBUSY" calendar component cannot be nested within another
calendar component. The "VFREEBUSY" calendar components MAY value that does not contain the
UTC designator nor does it reference a time zone. For example, 11 PM:

230000

Time values of this type are said to be
related "floating" and are not bound
to each other with any time zone in particular. They are used to represent the "RELATED-TO" property. Multiple
"VFREEBUSY" calendar components same
hour, minute, and second value regardless of which time zone is
currently being observed. For example, an event MAY be specified within defined that
indicates that an individual will be busy from 11:00 AM to 1:00 PM
every day, no matter which timezone the person is in. In these cases,
a local time MAY be specified. The recipient of an iCalendar
object. object
with a property value consisting of a local time, without any
relative time zone information, should interpret the value as being
fixed to whatever timezone the ATTENDEE is in at any given moment.
This permits means that two ATTENDEEs may participate in the grouping same event at
different UTC times; floating time should only be used where that is
reasonable behavior.

In most cases, a fixed time is desired. To properly communicate a
fixed time in a property value, either UTC time or local time with
time zone reference MUST be specified.

The use of Free/Busy information into
logical collections, such local time in a TIME value without the TZID property
parameter is to be interpreted as monthly groups of busy a local time information.

The "VFREEBUSY" value, regardless of
the existence of "VTIMEZONE" calendar component is intended for use components in the iCalendar
object methods involving requests for free
object.

FORM #2: DATE WITH UTC TIME

UTC time, requests for busy or absolute time, requests for both free and busy, and is identified by a LATIN CAPITAL LETTER Z
suffix character (ASCII decimal 90), the associated replies.

Free/Busy information can be expressed using UTC designator, appended to
the "FREEBBUSY"
property. This time value. For example, the following represents 0700 UTC:

070000Z

The TZID property provides a terse representation of parameter MUST NOT be applied to TIME properties
whose time values are specified in UTC.

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periods. One or more "FREEBUSY" properties MAY be specified in the
"VFREEBUSY" calendar component March 6, 1998

FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE

The local time with reference to describe time zone information form is
identified by the Free/Busy information.

Optionally, use the "DTSTART" and "DTEND" properties MAY be specified TZID property parameter to
express reference the start and end date and
appropriate time for all of the Free/Busy
information zone definition. TZID is discussed in detail in the "VFREEBUSY" calendar component. When present
section on Time Zone.

Example: The following represents 8:30 AM in a
"VFREEBUSY" calendar component, they should be specified prior to any
"FREEBUSY" properties. In a free time request, these properties MAY
be used New York, five hours
behind UTC, in combination with the "DURATION" property to express a
request for a duration of free time within a given window each of time.

The recurrence properties ("RRULE", "EXRULE", "RDATE", "EXDATE") are
not permitted within a "VFREEBUSY" calendar component. Any recurring
events are resolved into their individual busy time periods the three formats using the
"FREEBUSY" property.

The following "DTSTART"
property:

DTSTART:19980312T083000

DTSTART:19980312T133000Z

DTSTART;TZID=America-New York:19980312T083000

4.3.13 URI

Value Name: URI

Purpose: This value type is an example of a "VFREEBUSY" calendar component used to request free or busy time information:

BEGIN:VFREEBUSY
ATTENDEE;ROLE=ORGANIZER:MAILTO:jane_doe@host1.com
ATTENDEE:MAILTO:john_public@host2.com
DTSTART:19971015T050000Z
DTEND:19971016T050000Z
DTSTAMP:19970901T083000Z
SEQUENCE:0
UID:19970901T0830000-uid1@host1.com
END:VFREEBUSY identify values that contain a
uniform resource identifier (URI) type of reference to the property
value.

Formal Definition: The following data type is an example of a "VFREEBUSY" calendar component defined by the following
notation:

uri = <As defined by any IETF RFC>

Description: This data type might be used to reply reference binary
information, for values that are large, or otherwise undesirable to
include directly in the request with busy time information:

BEGIN:VFREEBUSY
ATTENDEE:MAILTO:john_public@host2.com
DTSTAMP:19970901T100000Z
SEQUENCE:0
UID:19970901T0830000-uid1@host1.com
FREEBUSY;VALUE=PERIOD:19971015T050000Z/PT8H30M,
19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M
URL:http://host2.com/pub/busy/jpublic-01.vcs
COMMENT:This iCalendar file contains busy time information for
the next three months.
END:VFREEBUSY

4.4.5 Alarm Component

A "VALARM" calendar component is a grouping of component properties
that is a reminder or alarm for an event or a to-do. object.

The "VALARM"
calendar component URI value formats in RFC 1738, RFC 2111 and any other IETF
registered value format MAY only be specified in a "VEVENT" or "VTODO"
calendar component. For example, it specified.

Any IANA registered URI format MAY define a reminder for be used. These include, but are
not limited to, those defined in RFC 1738 and RFC 2111.

When a
pending event or an overdue to-do.

The "DTSTART" property specifies the calendar date and time of day
that parameter value is a URI value type, the alarm will URI must be triggered. The
specified as a quoted-string value.

No additional content value MAY alternately be set to encoding (i.e., BACKSLASH character
encoding) is defined for this value type.

Example: The following is a URI for a network file:

http://host1.com/my-report.txt

4.3.14 UTC Offset

Value Name: UTC-OFFSET

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a DURATION, before or after the event or to-do, March 6, 1998

Purpose: This value type is used to identify properties that the alarm will
be triggered.

A "VALARM" calendar component contain
an offset from UTC to local time.

Formal Definition: The data type is defined by the following
notation:

alarmc = "BEGIN" ":" [WSP] "VALARM" CRLF
alarmprop
"END" ":" [WSP] "VALARM" CRLF

alarmprop

utc-offset = *attendee *attach 1*categories *comment [description]
dtstart duration *related repeat [summary]

The "VALARM" calendar component can only appear within either a
"VEVENT" or "VTODO" calendar component. time-numzone ;As defined above in time data
type

Description:

The "VALARM" calendar
components cannot PLUS SIGN character MUST be nested. specified for positive UTC offsets.

No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.

Example: The "CATEGORIES" property within the "VALARM" calendar component
specifies the type or combination following are UTC offsets are given for standard time
for New York (five hours behind UTC) and Geneva (one hour ahead of types
UTC):

-0500

+0100

4.4 iCalendar Object

The Calendaring and Scheduling Core Object is a collection of the alarm.
calendaring and scheduling information. Typically, this information
will consist of a single iCalendar object. However, multiple
iCalendar objects MAY be sequentially grouped together. The
"CATEGORIES" property value first
line and last line of AUDIO specifies an alarm that triggers
with an audio sound; the iCalendar object MUST contain a value pair of DISPLAY specifies
iCalendar object delimiter strings. The syntax for an alarm that
triggers with the "Calendar User Agent" displaying text; the value iCalendar
object is as follows:

icalobject = "BEGIN" ":" [WSP] "VCALENDAR" CRLF
icalbody
"END" ":" [WSP] "VCALENDAR" CRLF [icalobject]

The following is a simple example of
EMAIL specifies an alarm that triggers iCalendar object:

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
BEGIN:VEVENT
DTSTART:19970714T170000Z
DTEND:19970715T045959Z
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR

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4.5 Property

A property is the posting definition of an electronic
email message to one individual attribute describing a
calendar property or more email addresses; and a calendar component. A property takes the value of
PROCEDURE specifies an alarm that triggers form
defined by the execution of a
procedure.

In "contentline" notation defined in section 4.1.1.

The following is an AUDIO category example of alarm, the first "ATTACH" property in the
"VALARM" calendar component that specifies an audio sound file is
intended to be rendered as the alarm effect. If an "ATTACH" property
is specified that does not refer to an audio sound file, then it is
not used by this category of alarm. In addition, any "ATTENDEE",
"DESCRIPTION" or "SUMMARY" properties are not used by this category
of alarm.

In a DISPLAY category property:

DTSTART:19960415T133000Z

This memo places no imposed ordering of alarm, the "SUMMARY" property in the
"VALARM" calendar component is intended to be displayed as the alarm
effect. Any "ATTACH", "ATTENDEE" or "DESCRIPTION" properties in the
"VALARM" calendar component are not used by this category of alarm.

In within an EMAIL category
iCalendar object.

Property names, parameter names and parameter values (i.e.,
everything to the left of alarm, the intended alarm effect is to use ":" on a line) are case insensitive.
For example, the "DESCRIPTION" property in name "DUE" is the "VALARM" calendar component same as the "due" and "Due".

4.6 Calendar Components

The body text of an email message that is to be sent to the addresses
specified by any "ATTENDEE" iCalendar object consists of a sequence of calendar
properties present in the "VALARM" and one or more calendar component. components. The "SUMMARY" property in the "VALARM" calendar
component is intended
properties are attributes that apply to be used as the subject text for the email.
Any "ATTACH" properties calendar as a whole. The
calendar components are not used by this category collections of alarm.

In properties that express a PROCEDURE category of alarm, the first "ATTACH" property in
particular calendar semantic. For example, the
"VALARM" calendar component that specifies MAY
specify an event, a procedure or program is
intended to be invoked as the alarm effect. Any "ATTACH" properties
that do not refer to to-do, a procedure journal entry, time zone information, or program, then it
free/busy time information, or an alarm.

The body of the iCalenar object is not used defined by
this category of alarm. In addition, the "ATTENDEE", "DESCRIPTION" following notation:

icalbody = calprops 1*component

calprops = [calscale] [method] prodid version

component = 1*(eventc / todoc / journalc / freebusyc /
/ timezonec / x-name / iana-token)

An iCalendar object must include the "PRODID" and "SUMMARY" properties "VERSION" calendar
properties. In addition, it must include at least one calendar
component. Special forms of iCalendar objects are not possible to publish
just busy time (i.e., only a "VFREEBUSY" calendar component) or time
zone (i.e., only a "VTIMEZONE" calendar component) information. In
addition, a complex iCalendar object is possible that is used by this category to
capture a complete snapshot of alarm.
"Calendar User Agents" that receive the contents of a calendar (e.g.,
composite of many different calendar components). More commonly, an
iCalendar object with this will consist of just a single "VEVENT", "VTODO" or
"VJOURNAL" calendar component.

4.6.1 Event Component

Component Name: "VEVENT"

Purpose: Provide a grouping of component properties that describe an
event.

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category of alarm, should allow the "Calendar User" to disable or
otherwise ignore this category of alarm. While a very useful alarm
capability, the PROCEDURE category of alarm should be treated March 6, 1998

Format Definition: A "VEVENT" calendar component is defined by the
"Calendar User Agent" as a potential security risk.

The
following is an example of the "VALARM" calendar component:

BEGIN:VALARM
DTSTART:19970317T133000Z
REPEAT:4
DURATION:PT15M
CATEGORIES:DISPLAY,AUDIO
ATTACH:ftp://host.com/pub/sounds/bell-01.wav
SUMMARY:Breakfast meeting with executive team at 8:30 AM
END:VALARM

4.4.6 Timezone Component

The "VTIMEZONE" notation:

eventc = "BEGIN" ":" [WSP] "VEVENT" CRLF
eventprop *alarmc
"END" ":" [WSP] "VEVENT" CRLF

eventprop = *attach *attendee *categories [class] *comment
*contact [created] [description] [dtend / duration]
dtstart *exdate *exrule [geo] [last-mod] [location]
[organizer] [priority] [rstatus] *related *resources
*rdate *rrule dtstamp [seq] [status] summary
[transp] uid [url] [recurid]

Description: A "VEVENT" calendar component is used to define a time zone.

A time zone is unambiguously defined by the set grouping of component
properties and an OPTIONAL "VALARM" calendar component that represent
a scheduled amount of time measurement
rules determined by the governing body for on a given geographic area.
These rules describe at calendar. For example, it MAY be an
activity; such as a minimum the base offset one-hour, department meeting from UTC for the
time zone, often referred 8:00 AM to 9:00
AM, tomorrow. Generally, these events will take up time on an
individual calendar. Hence, the event will appear as an opaque
interval in a search for busy time. Alternately, the Standard Time offset. Many
locations adjust their Standard event MAY have
its Time forward or backward by one hour, Transparency set to "TRANSPARENT" in order to accommodate seasonal changes in number prevent
blocking of daylight hours,
often referred the event in searches for busy time.

The "VEVENT" is also the calendar component used to as Daylight Saving Time. Some locations adjust
their time by specify an
anniversary or daily reminder within a fraction calendar. These events have a
DATE value type for the "DTSTART" and "DTEND" properties instead of
the default data type of DATE-TIME. If such a "VEVENT" has an hour. Standard Time is also known end
time, it MUST be specified as
Winter Time. Daylight Saving Time is also known as Advanced Time,
Summer Time, or Legal Time in certain countries. a DATE value also. The following table
shows anniversary type
of "VEVENT" MAY span more than one date (i.e, "DTEND" property value
is set to a calendar date after the changes in time zone rules "DTSTART" property value).

The "DTSTART" property for a "VEVENT" specifies the eastern United States.

Effective Transition Rule
Date (Date/Time) Offset Abbreviation

1920-1920 last Sun in Mar, 02:00 _0400 EDT

1920-1920 last Sun in Oct, 02:00 _0500 EST

1921-1966 last Sun in Apr, 02:00 _0400 EDT

1921-1954 last Sun in Sep, 02:00 _0500 EST

1955-1966 last Sun in Oct, 02:00 _0500 EST

1967-* last Sun in Oct, 02:00 _0500 EST

1967-1973 last Sun in Apr, 02:00 _0400 EDT

1974-1974 Jan 6, 02:00 -0400 EDT

1975-1975 Feb 23, 02:00 -0400 EDT

1976-1986 last Sun in Apr, 02:00 _0400 EDT

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1987-* first Sun in Apr, 02:00 _0400 EDT

Interoperability between two calendaring and scheduling applications,
especially for inclusive start
of the event. For recurring events, to-dos or journal entries, is
dependent on it also specifies the ability to capture and convey date and time
information very first
instance in an unambiguous format. The specification of current
time zone information is integral to this behavior. the recurrence set. The "VTIMEZONE" calendar component is "DTEND" property for a grouping of "VEVENT"
calendar component
properties that define a time zone description. The time zone
description specifies the effective Standard Time or Daylight Savings
Time rules for non-inclusive end of the event. For
cases where a particular time zone. The "VTIMEZONE" "VEVENT" calendar component cannot be nested within other calendar components. The
"VTIMEZONE" calendar component MAY be specified multiple times. If specifies a "DTSTART"
property with a DATE data type but no "DTEND" property, the "VTIMEZONE" calendar component events
non-inclusive end is missing, the recipient should
assume all local times are relative to end of the recipient's time zone. The
"VTIMEZONE" calendar component should be date specified in the iCalendar
object before any other calendar components.

A "VTIMEZONE" calendar component is defined by the following
notation:

timezonec = "BEGIN" ":" [WSP] "VTIMEZONE" CRLF
tzprop
"END" ":" [WSP] "VTIMEZONE" CRLF

tzprop = *comment [daylight] dtstart [rdate / rrule]
[tzname] tzoffset

The "VTIMEZONE"
"DTSTART" property. For cases where a "VEVENT" calendar component is important for correct
interpretation of individual as well as recurring calendar components
that span
specifies a time zone transition. For example, from EST to EDT. The
exception to this are calendar components that are considered
floating (i.e., occurs at "DTSTART" property with a particular local time DATE-TIME data type but no matter what time
zone you are in). If
"DTEND" property, the iCalendar object contains a non-floating
calendar component that has a recurring date pattern (i.e., includes event ends on the "RRULE" property) or a list of same calendar date and local time values (i.e.,
includes
of day specified by the "RDATE" property), one or more "VTIMEZONE" "DTSTART" property.

The "VEVENT" calendar
components component MUST be specified, such that for the given range of the
recurrence (i.e., include the earliest instance to latest instance), there is
valid time zone information for all instances. "DTSTAMP",
"DTSTART", "SUMMARY" and "UID" properties. In other words, if all
of the instances of addition, it MUST
include the pattern "SEQUENCE" property, if it's value is entirely within one offset
observance, (e.g., all are in Standard Time), only one "VTIMEZONE" greater than zero.

The "VEVENT" calendar component need cannot be present. If a time zone transition is
crossed, then other "VTIMEZONE" nested within another
calendar components are needed.
Further, if there are known changes to the rules for the time zone,
even more "VTIMEZONE" component. The "VEVENT" calendar components are needed.

Each "VTIMEZONE" calendar component consists of several properties:

The "DAYLIGHT" property is a BOOLEAN value indicating Standard Time
(FALSE) MAY be related
to each other or Daylight Savings Time (TRUE). The default for DAYLIGHT is
FALSE to a "VTODO" or Standard Time. "VJOURNAL" calendar component with
the "RELATED-TO" property.

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Example: The "DTSTART" property in this usage following is a fully specified DATE-TIME
value, including the UTC offset, indicating the effective start date
and time for the time zone information. For example, 19671029T020000-
0400 represents the time at which an example of the transition "VEVENT" calendar
component used to Standard Time
took effect in 1967 represent a meeting that will also be opaque to
searches for the eastern United States. busy time:

BEGIN:VEVENT
UID:19970901T130000Z-123401@host.com
DTSTAMP:19970901T1300Z
DTSTART:19970903T163000Z
DTEND:19970903T190000Z
SUMMARY:Annual Employee Review
CLASS:PRIVATE
CATEGORIES:BUSINESS,HUMAN RESOURCES
END:VEVENT

The "TZOFFSET" property following is a UTC-OFFSET value indicating an example of the UTC
offset "VEVENT" calendar component used
to represent a reminder that will not be opaque, but rather
transparent, to searches for the time zone (Standard Time or Daylight Savings Time). busy time:

BEGIN:VEVENT
UID:19970901T130000Z-123402@host.com
DTSTAMP:19970901T1300Z
DTSTART:19970401T163000Z
DTEND:19970402T010000Z
SUMMARY:Laurel is in sensitivity awareness class.
CLASS:PUBLIC
CATEGORIES:BUSINESS,HUMAN RESOURCES
TRANSP:TRANSPARENT
END:VEVENT

The "TZNAME" property following is an example of the customary name "VEVENT" calendar component used
to represent an anniversary that will occur annually. Since it takes
up no time, it will not appear as opaque in a search for busy time;
no matter what the time zone.

The "RRULE" property indicates value of the recurrence rule for "TRANSP" property indicates:

4.6.2 To-do Component

Component Name: VTODO

Purpose: Provide a grouping of calendar properties that describe a
to-do.

Formal Definition: A "VTODO" calendar component is defined by the transition
to this time zone.
following notation:

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todoc = "BEGIN" ":" [WSP] "VTODO" CRLF
todoprop *alarmc
"END" ":" [WSP] "VTODO" CRLF

todoprop = *attach *attendee *categories [class] *comment
[completed] *contact [created] [description] dtstamp
[dtstart] [due / duration] *exdate *exrule [geo]
[last-mod] [location] [organizer] [percent] priority
[rstatus] *related *resources *rdate *rrule
[recurid] [seq] [status] summary uid [url]

Description: A "VTODO" calendar component is a grouping of component
properties and an OPTIONAL "VALARM" calendar component that represent
an action-item or assignment. For example, in the United States, the transition
from Standard Time it MAY be an item of work
assigned to Daylight Saving Time occurs on the first Sunday an individual; such as "turn in April at 02:00. If a recurrence rule describing travel expense today".

The "VTODO" calendar component MUST include the transition is
known to have an effective end date, "DTSTAMP",
"PRIORITY", "SUMMARY" and "UID" properties. In addition, it MUST
include the UNTIL recurrence rule
parameter "SEQUENCE" property, if it's value is used greater than zero.

The "VTODO" calendar component cannot be nested within another
calendar component. If "VTODO" calendar components need to be related
to each other or to a "VTODO" or "VJOURNAL" calendar component, they
can specify that end date and time. If the
recurrence rule for a particular observance (Daylight Saving Time) is
changing, then relationship with the UNTIL of the first rule will be equal to the last
valid instance (the last date-time) of this particular rule. See
example below.

Alternatively, "RELATED-TO" property.

A "VTODO" calendar component without the "RDATE" property can be used. The "RDATE" property
is "DTSTART" and "DUE" (or
"DURATION") properties specifies a property that indicates the individual dates and/or times to-do that
the transition takes effect. The values supplied for "RDATE" property
for is associated with each "VTIMEZONE" calendar component MUST provide valid time zone
information of all instances of the recurrence specified for the
successive calendar component to which this time zone information dates, until it is to be
applied. completed.

Example: The following are examples is an example of the "VTIMEZONE" a "VTODO" calendar component:

This is

BEGIN:VTODO
UID:19970901T130000Z-123404@host.com
DTSTAMP:19970901T1300Z
DTSTART:19970415T133000Z
DUE:19970416T045959Z
SUMMARY:1996 Income Tax Preparation
CLASS:CONFIDENTIAL
CATEGORIES:FAMILY,FINANCE
PRIORITY:1
STATUS:NEEDS-ACTION
END:VEVENT

4.6.3 Journal Component

Component Name: VJOURNAL

Purpose: Provide a simple example showing time zone information for the
Eastern United States using "RDATE" property. Note grouping of component properties that this is only
suitable for describe a recurring event that starts on or later than 1997,
April 6, at 02:00:00 EST (i.e.,
journal entry.

Formal Definition: A "VJOURNAL" calendar component is defined by the earliest effective transition
date and time) and ends no later than 1998, April 7, 02:00:00 EST
(i.e., latest valid date and time for EST in this scenario). For
example, this can be used for a recurring event that ocurrs every
Friday, 8am-9am, starting June 1, 1997, ending Dec 31, 1997.

BEGIN:VTIMEZONE
DAYLIGHT:FALSE
RDATE:19971026T020000-0400
TZOFFSET:-0500
TZNAME:EST
END:VTIMEZONE

BEGIN:VTIMEZONE
DAYLIGHT:TRUE
RDATE:19970406T020000-0500
TZOFFSET:-0400
TZNAME:EDT
END:VTIMEZONE
following notation:

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This is a simple example showing the current time zone rules for the
Eastern United States using March 6, 1998

journalc = "BEGIN" ":" [WSP] "VJOURNAL" CRLF
jourprop
"END" ":" [WSP] "VJOURNAL" CRLF

jourprop = *attach *attendee *categories [class] *comment
*contact [created] description dtstart dtstamp
*exdate *exrule [last-mod] [organizer] [recurid]
*related *rdate *rrule [rstatus] [seq] summary
uid [url]

Description: A "VJOURNAL" calendar component is a RRULE recurrence pattern. Note grouping of
component properties that
there represent one or more descriptive text
notes on a particular calendar date. The "DTSTART" property is no effective end date used
to either of specify the Standard Time or
Daylight Time rules. This information would be valid for a
recurrening event starting today and continuing on into calendar date that the known
future.

BEGIN:VTIMEZONE
DAYLIGHT:FALSE
DTSTART:19671029T020000-0400
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSET:-0500
TZNAME:EST
END:VTIMEZONE

BEGIN:VTIMEZONE
DAYLIGHT:TRUE
DTSTART:19870405T020000-0500
RRULE: FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZOFFSET:-0400
TZNAME:EDT
END:VTIMEZONE

This journal entry is an example showing associated
with. Generally, it will have a ficticious set DATE value data type, but it MAY also
be used to specify a DATE-TIME value data type. Examples of rules a journal
entry include a daily record of a legislative body or a journal entry
of individual telephone contacts for the Eastern
United States, where the Daylight Time rule has an effective end date
(i.e., after that date, Daylight Time is no longer observed).

BEGIN:VTIMEZONE
DAYLIGHT:FALSE
DTSTART:19671029T020000-0400
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSET:-0500
TZNAME:EST
END:VTIMEZONE

BEGIN:VTIMEZONE
DAYLIGHT:TRUE
DTSTART:19870405T020000-0500
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T020000-0500
TZOFFSET:-0400
TZNAME:EDT
END:VTIMEZONE

This is day or an example showing a fictitious set ordered list of rules
accomplishments for the Eastern
United States, where the first Daylight Time rule has an effective
end date. There is day. The "VJOURNAL" calendar component can
also be used to associate a second Daylight Time rule that picks document with a calendar date.

The "VJOURNAL" calendar component does not take up where
the other left off.

BEGIN:VTIMEZONE
DAYLIGHT:FALSE
DTSTART:19671029T020000-0400
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSET:-0500

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TZNAME:EST
END:VTIMEZONE

BEGIN:VTIMEZONE
DAYLIGHT:TRUE
DTSTART:19870405T020000-0500
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T020000-0500
TZOFFSET:-0400
TZNAME:EDT
END:VTIMEZONE

BEGIN:VTIMEZONE
DAYLIGHT:TRUE
DTSTART:19990327T020000-0500
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
TZOFFSET:-0400
TZNAME:EDT
END:VTIMEZONE

4.5 Calendar Properties

The Calendar Properties are attributes that apply to the iCalendar
object, as time on a whole. These properties do
calendar. Hence, it does not appear within play a calendar
component. They should be specified after the "BEGIN:VCALENDAR"
property and prior role in free or busy time
searches - - it is as though it has a time transparency value of
TRANSPARENT. It is transparent to any such searches.

The "VJOURNAL" calendar component.

4.5.1 Calendar Scale

This property is identified by the property name CALSCALE. This
property defines the calendar scale used for component MUST include the calendar information
specified in "DTSTAMP",
"DTSTART", "DESCRIPTION", "SUMMARY" an "UID" properties. In addition,
it MUST include the iCalendar object. This memo "SEQUENCE" property, if it's value is based on the
Gregorian calendar scale. greater
than zero.

The Gregorian "VJOURNAL" calendar scale is assumed if
this property is not specified in the iCalendar object. It is
expected that other component cannot be nested within another
calendar scales will component. If "VJOURNAL" calendar components need to be defined in
related to each other
specifications or by future versions of this memo.

The property is defined by to a "VEVENT" or "VTODO" calendar component,
they can specify a relationship with the following notation:

calscale = "CALSCALE" ":" [WSP] calvalue CRLF

calvalue = "GREGORIAN" / iana-token "RELATED-TO" property.

Example: The following is an example of this property:

CALSCALE:GREGORIAN

The data type for this property is TEXT.

4.5.2 Method

This property is identified by the property name METHOD. This
property defines the iCalendar object method associated with the "VJOURNAL" calendar object. When used in a MIME message entity, the value of
component:

BEGIN:VJOURNAL
UID:19970901T130000Z-123405@host.com
DTSTAMP:19970901T1300Z
DTSTART;VALUE=DATE:19970317
SUMMARY:Staff meeting minutes
DESCRIPTION:1. Staff meeting: Participants include Joe\, Lisa
and Bob. Aurora project plans were reviewed. There is currently
no budget reserves for this property MUST be the same as the Content-Type "method" parameter project. Lisa will escalate to
management. Next meeting on Tuesday.
2. Telephone Conference: ABC Corp. sales representative called
to discuss new printer. Promised to get us a demo by Friday.
3. Henry Miller (Handsoff Insurance): Car was totaled by tree.
Is looking into a loaner car. 654-2323 (tel).
END:VJOURNAL

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value. This property can only appear once within the iCalendar
object.

The property March 6, 1998

4.6.4 Free/Busy Component

Component Name: VFREEBUSY

Purpose: Provide a grouping of component properties that describe
either a request for free/busy time, describe a response to a request
for free/busy time or describe a published set of busy time.

Formal Definition: A "VFREEBUSY" calendar component is defined by the
following notation:

method

freebusyc = "METHOD" "BEGIN" ":" [WSP] "VFREEBUSY" CRLF
fbprop
"END" ":" [WSP] profvalue "VFREEBUSY" CRLF

profvalue

fbprop = <Any IANA registered iCalendar object method.>

The following is an example fbrequest / fbreply / busytime

fbrequest = 1*attendee dtstart dtend [duration] *comment dtstamp
[last-mod] [seq] uid
;This set of this property when the iCalendar
object properties is used to request a meeting:

METHOD: REQUEST

The data type for this property is TEXT.

4.5.3 Product Identifier

This property free/busy time request.

fbreply = 1*attendee [created] *comment [dtstart dtend] dtstamp
1*freebusy [last-mod] [rstatus] [seq] uid
[url]
;This set of properties is identified by the property name PRODID. This
property specifies the identifier used for the product that created the
iCalendar object. The vendor free/busy time reply.

busytime = attendee dtstamp dtstart dtend *comment 1*freebusy
[url]

Description: A "VFREEBUSY" calendar component is a grouping of the implementation should assure
component properties that
this is represents either a globally unique identifier; using some technique such as an
ISO 9070 FPI value. This calendar property MUST be specified in the
iCalendar object but can only appear once.

This property should not be request for, a reply to
a request for free or busy time information or a published set of
busy time information.

When used to alter request free/busy time information, the interpretation of an
iCalendar object beyond "VFREEBUSY"
calendar component MUST include the semantics specified in this memo. For
example, "ATTENDEE", "DTSTAMP", "DTSTART",
"DTEND", and "UID" properties. In addition, it MUST include the
"SEQUENCE" property, if it's value is not to be greater than zero.

When used to further reply to a request for free/busy time, the understanding of non-
standard "VFREEBUSY"
calendar component MUST include the "ATTENDEE", "DTSTAMP",
"FREEBUSY", and "UID" properties.

The property In addition, it MUST include the
"SEQUENCE" property, if it's value is defined by greater than zero.

When used to publish busy time, the following notation:

prodid = "PRODID" ":" [WSP] pidvalue CRLF

pidvalue = text
;Any text that describes "VFREEBUSY" calendar component
MUST include the product and version
;and that is generally assured of being unique. "ATTENDEE", "DTSTAMP", "DTSTART", "DTEND",
"FREEBUSY" properties.

The following is "VFREEBUSY" calendar component cannot be nested within another
calendar component. Multiple "VFREEBUSY" calendar components MAY be
specified within an example of this property:

PRODID:-//ABC Corporation//NONSGML My Product//EN

The data type for this property is TEXT.

4.5.4 Source iCalendar object. This property is identified by permits the property name SOURCE. This
property is defined by the [MIME DIR] memo. In this memo, the
property identifies the URI for the source grouping of the iCalendar object.
The URI is useful for accessing the iCalendar object using a calendar
access protocol.

The property is defined by the following notation:
Free/Busy information into logical collections, such as monthly
groups of busy time information.

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source = "SOURCE" ":" [WSP] uri CRLF

The following are examples of this property:

SOURCE:http://xyz.corp.com/corp-cals/1997-events.or4

SOURCE:http://xyz.corp.com/calendars/~jdoe March 6, 1998

The data type for this property is URI.

4.5.5 Source Name

This property is identified by the property name NAME. This property "VFREEBUSY" calendar component is defined by the [MIME DIR] memo. The property identifies the
displayable, presentation name intended for the source of the iCalendar
object. The source name is a useful text to associate in the user-
interface of an application with the value use in the SOURCE property.

The property is defined by the following notation:

name = "NAME" ":" [WSP] text CRLF

The following is an example of this property:

NAME:1997 Events Calendar iCalendar
object methods involving requests for XYZ Corporation

The data type free time, requests for this property is TEXT.

4.5.6 Version

This property is identified by busy
time, requests for both free and busy, and the property name VERSION. associated replies.

Free/Busy information can be expressed using the "FREEBBUSY"
property. This property specifies provides a terse representation of time
periods. One or more "FREEBUSY" properties MAY be specified in the identifier corresponding
"VFREEBUSY" calendar component to describe the highest
version number or the minimum and maximum range of Free/Busy information.

When present in a "VFREEBUSY" calendar component, the MIME
Calendaring "DTSTART" and Scheduling Content Type specification supported by
the implementation that created the iCalendar object. A value of
"2.0" corresponds
"DTEND" properties SHOULD be specified prior to this memo. This calendar any "FREEBUSY"
properties. In a free time request, these properties MAY be used in
combination with the "DURATION" property MUST appear to express a request for a
duration of free time within the iCalendar object but can only appear once. a given window of time.

The property is defined by recurrence properties ("RRULE", "EXRULE", "RDATE", "EXDATE") are
not permitted within a "VFREEBUSY" calendar component. Any recurring
events are resolved into their individual busy time periods using the
"FREEBUSY" property.

Example: The following notation:

version = "VERSION" ":" [WSP] vervalue CRLF

vervalue = "2.0" ;This memo
/ maxver
/ (minver ";" [WSP] maxver)

minver = <A IANA registered iCalendar version identifier>
;Minimum iCalendar version is an example of a "VFREEBUSY" calendar
component used to create the iCalendar object

maxver = <A IANA registered iCalendar version identifier>
;Maximum iCalendar version request free or busy time information:

BEGIN:VFREEBUSY
ORGANIZER:MAILTO:jane_doe@host1.com
ATTENDEE:MAILTO:john_public@host2.com
DTSTART:19971015T050000Z
DTEND:19971016T050000Z
DTSTAMP:19970901T083000Z
SEQUENCE:0
UID:19970901T0830000-uid1@host1.com
END:VFREEBUSY

The following is an example of a "VFREEBUSY" calendar component used
to create reply to the request with busy time information:

BEGIN:VFREEBUSY
ATTENDEE:MAILTO:john_public@host2.com
DTSTAMP:19970901T100000Z
SEQUENCE:0
UID:19970901T0830000-uid1@host1.com
FREEBUSY;VALUE=PERIOD:19971015T050000Z/PT8H30M,
19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M
URL:http://host2.com/pub/busy/jpublic-01.vcs
COMMENT:This iCalendar object file contains busy time information for
the next three months.
END:VFREEBUSY

The following is an example of this property: a "VFREEBUSY" calendar component used
to published busy time information.

BEGIN:VFREEBUSY
ATTENDEE:jsmith@host.com
DTSTART:19980313T141711Z

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VERSION:2.0

The data type for this property is TEXT.

4.6 March 6, 1998

DTEND:19980410T141711Z
FREEBUSY:19980314T233000Z/19980315T003000Z
FREEBUSY:19980316T153000Z/19980316T163000Z
FREEBUSY:19980318T030000Z/19980318T040000Z
URL:http://www.host.com/calendar/busytime/jsmith.ifb
END:VFREEBUSY

4.6.5 Timezone Component Properties

The following

Component Name: VTIMEZONE

Purpose: Provide a grouping of component properties MAY appear within calendar components, as
specified by each component property definition.

4.6.1 Attachment

This property is identified by the property name ATTACH. The property
provides the capability to associate an external object with a
calendar component. For example, a document to be reviewed at a
scheduled event or the description of the process steps for that defines a to-do.
The property MAY only be specified within "VEVENT", "VTODO",
"VJOURNAL", or "VALARM"
time zone.

Formal Definition: A "VTIMEZONE" calendar components. This property MAY be
specified multiple times within an iCalendar object.

The property component is defined by the
following notation:

attach

timezonec = ("ATTACH" "BEGIN" ":" [WSP] uri CRLF) "VTIMEZONE" CRLF

tzid [last-mod] [tzurl] 1*(standardc /
("ATTACH" ";" daylightc)

"END" ":" [WSP] "ENCODING" "=" "b" ";" "VTIMEZONE" CRLF

standardc = "BEGIN" ":" [WSP]
"VALUE" "=" "text" "STANDARD" CRLF

tzprop

"END" ":" [WSP] folded-b

The following are examples of this property:

ATTACH:CID:jsmith.part3.960817T083000.xyzMail@host1.com

ATTACH:FTP://xyzCorp.com/pub/reports/r-960812.ps

The default data type for this property is URI. The data type MAY
also be reset to TEXT in order to include inline binary encoded
content information.

4.6.2 Attendee

This property "STANDARD" CRLF

daylightc = "BEGIN" ":" [WSP] "DAYLIGHT" CRLF

tzprop

"END" ":" [WSP] "DAYLIGHT" CRLF

tzprop = *comment dtstart [rdate / rrule]

*tzname tzoffsetto tzoffsetfrom

Description: A time zone is identified unambiguously defined by the property name ATTENDEE. The
property defines an attendee within a calendar component. The
property MAY only be specified within the "VEVENT", "VTODO",
"VJOURNAL", "VFREEBUSY" and "VALARM" calendar components.

The property has the property parameters TYPE, for the type of
attendee, ROLE, for the intended role set of time
measurement rules determined by the attendee; STATUS, governing body for a given
geographic area. These rules describe at a minimum the status of the attendee's participation; RSVP, base offset
from UTC for indicating
whether the favor of a reply is requested; EXPECT, time zone, often referred to indicate the
expectation of as the attendee's participation Standard Time
offset. Many locations adjust their Standard Time forward or
backward by the originator;
MEMBER, to indicate the groups that the attendee belongs to;
DELEGATED-TO, one hour, in order to indicate the people that the original request was
delegated to; and DELEGATED-FROM, accommodate seasonal changes in
number of daylight hours, often referred to indicated whom the request was
delegated from.

A recipient delegated as Daylight Saving Time.
Some locations adjust their time by a request MUST inherit the RSVP and EXPECT
values from fraction of an hour. Standard
Time is also known as Winter Time. Daylight Saving Time is also
known as Advanced Time, Summer Time, or Legal Time in certain
countries. The following table shows the attendee that delegated changes in time zone rules
for the request to them. eastern United States starting from 1967. Each line
represents a description or rule for a particular observance.

Effective Observance Rule

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Multiple attendees MAY be specified by including multiple "ATTENDEE"
properties within the MIME March 6, 1998

Date (Date/Time) Offset Abbreviation

1967-* lastSun in Oct, 02:00 -0500 EST

1967-1973 last Sun in Apr, 02:00 -0400 EDT

1974-1974 Jan 6, 02:00 -0400 EDT

1975-1975 Feb 23, 02:00 -0400 EDT

1976-1986 last Sun in Apr, 02:00 -0400 EDT

1987-* first Sun in Apr, 02:00 -0400 EDT

Interoperability between two calendaring entity.

The property data type default and scheduling applications,
especially for recurring events, to-dos or journal entries, is CAL-ADDRESS. The property data type
MAY also be set
dependent on the ability to URI. This provides a useful mechanism to allow
more than just the address capture and convey date and time
information in an unambiguous format. The specification of the attendee current
time zone information is integral to be referenced. this behavior.

If present, the
value is "VTIMEZONE" calendar component defines the set of
Standard Time and Daylight Saving Time observances (or rules) for a URI, then it
particular time zone for a given interval of time. The "VTIMEZONE"
calendar component cannot be nested within other calendar components.
Multiple "VTIMEZONE" calendar components MAY exist in an iCalendar
object. In this situation, each "VTIMEZONE" MUST represent a unique
time zone definition. This is necessary for some classes of events,
such as airline flights, that start in one time zone and end in
another.

The "VTIMEZONE" calendar component MUST be able present if the iCalendar
object contains an RRULE that generates dates on both sides of a time
zone shift (e.g. both in Standard Time and Daylight Saving Time)
UNLESS the iCalendar object intends to convey a floating time (See
the section "4.1.10.11 Time" for proper interpretation of floating
time). It MAY be resolved to present if the iCalendar object does not contain
such a calendar
address.

The property RRULE. In addition, if a RRULE is defined by present, there must be valid
time zone information for all recurrence instances.

The "VTIMEZONE" calendar component MUST include the following notation:

attendee = "ATTENDEE" *(";" [WSP] parameter)
*(";" [WSP] attparam) ":" [WSP]
(cal-address / uri) CRLF
;Value "TZID" property
and at least one definition of a standard or daylight component. The
standard or daylight component MUST match default include the "DTSTART",
"TZOFFSETFROM" and "TZOFFSETTO" properties.

Each "VTIMEZONE" calendar component consists of a collection of one
or explicit data type

attparam = typeparm / roleparm / statusparm / rsvpparm
/ expectparm / memberparm / deletoparm / delefromparm

typeparm = "TYPE" "="
("INDIVIDUAL" ; An individual
/ "GROUP" ; A group more sub-components that describe the rule for a particular
observance (either a Standard Time or a Daylight Saving Time
observance). The "STANDARD" sub-component consists of individuals
/ "RESOURCE" ; A physical resource
/ "ROOM" ; A room resource
/ "UNKNOWN") ; Otherwise not known
;Default value is INDIVIDUAL

roleparm = "ROLE" "="
("ATTENDEE" ; Indicates a regular attendee
/ "OWNER" ; Indicates owner collection of event or to-do
/ "ORGANIZER" ; Indicates organizer
properties that describe Standard Time. The "DAYLIGHT" sub-component
consists of event or to-do
/ "DELEGATE") ; Indicates delegate to event or to-do
;Default is ATTENDEE

statusparm = "STATUS" "="
("NEEDS-ACTION" ; Indicates event or to-do needs action
/ "ACCEPTED" ; Indicates event or to-do accepted
/ "DECLINED" ; Indicates event or to-do not accepted
/ "TENTATIVE" ; Indicates event or to-do tentatively
; accepted. Status MAY change in the future.
/ "COMPLETED" ; Indicates to-do was completed.
; COMPLETED property has date/time completed.
/ "IN-PROCESS" ;Indicates to-do is in the process a collection of
; being completed.
/ "DELEGATED" ; Indicates event or to-do delegated
; to another ATTENDEE
/ "CANCELLED") ; Indicates event or to-do cancelled properties that describe Daylight Saving
Time. In general this collection of properties consists of:

- the first onset date-time for
; ATTENDEE
;Default is NEEDS-ACTION

rsvpparm = "RSVP" "="
("TRUE" ; Indicates response requested
/ "FALSE") ; Indicates no response needed
;Default is FALSE the observance

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expectparm = "EXPECT" "="
("FYI" ; Indicates request is March 6, 1998

- the last onset date-time for your info
/ "REQUIRE" ; Indicates presence is required
/ "REQUEST") ; Indicates presence the observance, if a last onset
is requested
;Default known.

- the offset to be applied for the observance

- a rule that describes the day and time when the observance
takes effect

- an optional name for the observance

For a given time zone, there may be multiple unique definitions of
the observances over a period of time. Each observance is FYI

memberparm = "MEMBER" "=" cal-address *("," [WSP] cal-address)
; Indicates described
using either a group "STANDARD" or mailing list

deletoparm = "DELEGATED-TO" "=" cal-address *("," [WSP]
cal-address)
; Indicates who the request "DAYLIGHT" sub-component. The collection
of these sub-components is delegated used to

delefromparm = "DELEGATED-FROM" "=" cal-address *("," [WSP]
cal-address)
;Indicates who describe the request time zone for a given
period of time. The offset to apply at any given time is delegated found by
locating the observance that has the last onset date and time before
the time in question, and using the offset value from that
observance.

The following are examples of this property's use for top-level properties in a to-do:

ATTENDEE;ROLE=OWNER;STATUS=COMPLETED:MAILTO:jsmith@host1.com
ATTENDEE;MEMBER="MAILTO:DEV-GROUP@host2.com":
MAILTO:joecool@host2.com
ATTENDEE;DELEGATED-FROM="MAILTO:immud@host3.com":
MAILTO:ildoit@host1.com "VTIMEZONE" calendar component are:

The following mandatory "TZID" property is an example a text value that uniquely
identifies the VTIMZONE calendar component within the scope of this property used for specifying
multiple attendees to an event:

ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED: MAILTO:John Smith
<jsmith@host1.com>
ATTENDEE;ROLE=ATTENDEE;STATUS=TENTATIVE:MAILTO:Henry Cabot
<hcabot@host2.com>
ATTENDEE;ROLE=DELEGATE;STATUS=ACCEPTED:MAILTOJane Doe
<jdoe@host1.com>
iCalendar object.

The following optional "LAST-MODIFIED" property is an example of a UTC value that specifies
the date and time that this time zone definition was last updated.

The optional "TZURL" property with the is url value specified
as an URI reference that points to a vCard published
VTIMEZONE definition.

The collection of properties that contains the information about are used to define the attendee:

ATTENDEE;ROLE=ATTENDEE;STATUS=ACCEPTED;VALUE=URI:
http://www.xyz.com/~myvcard.vcf STANDARD and
DAYLIGHT sub-components include:

The following mandatory "DTSTART" property gives the effective onset date and
local time for the time zone sub-component definition. "DTSTART" in
this usage MUST be specified as a local DATE-TIME value.

The mandatory "TZOFFSETFROM" property gives the UTC offset which is an example
in use when the onset of this property time zone observance begins.
"TZOFFSETFROM" is combined with "delegatee" and
"delegator" information "DTSTART" to define the effective
onset for an event:

ATTENDEE;ROLE=OWNER;STATUS=ACCEPTED:MAILTO:John Smith
<jsmith@host1.com>

ATTENDEE;ROLE=DELEGATE;STATUS=TENTATIVE;DELEGATED-FROM=
"MAILTO:iamboss@host2.com":MAILTO:Henry Cabot<hcabot@host2.com>

ATTENDEE;ROLE=ATTENDEE;STATUS=DELEGATED;DELEGATED-TO=
"MAILTO:hcabot@host2.com:MAILTO:iamboss(The Big Cheese)@host2.com the time zone sub-component definition. For example, the
following represents the time at which the observance of Standard
Time took effect in 1967 for the eastern United States:

DTSTART:19671029T020000

TZOFFSETFROM:-0400

The mandatory "TZOFFSETTO " property gives the UTC offset for the
time zone sub-component (Standard Time or Daylight Saving Time) when
this observance is in use.

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ATTENDEE;ROLE=DELEGATE;STATUS=ACCEPTED:MAILTO:Jane Doe
<jdoe@host1.com> March 6, 1998

The default data type for this optional "TZNAME" property is CAL-ADDRESS. The data type
MAY be reset to URI; in which case the value is a location or message
that contains customary name for the information that is to time
zone. It may be used specified multiple times, to specify allow for specifying
multiple language variants of the
attendee address.

4.6.3 Categories time zone names. This property is identified could be used
for displaying dates.

If specified, the onset for the observance defined by the property name CATEGORIES. This
property defines time zone
sub-component is defined by either the categories for a calendar component. The
property MAY "RRULE" or "RDATE" property.
If neither are specified, only one sub-component can be specified within the "VEVENT", "VTODO" or "VJOURNAL"
calendar component with an arbitrary text value. In in
the "VALARM" "VTIMEZONE" calendar component and it is assumed that the property MUST be single
observance specified to declare is always in effect.

The "RRULE" property defines the
alarm category. More than one category MAY be specified as a list recurrence rule for the onset of
categories separated by the COMMA character (ASCII decimal 44).

The properties is
observance defined by the following notation:

categories = "CATEGORIES" *(";" [WSP] parameter) ":" [WSP]
catvalue CRLF

catvalue = cat1value *["," [WSP] cat1value]
/ cat2value *["," [WSP] cat2value]

cat1value = "ANNIVERSARY" / "APPOINTMENT" / "BUSINESS"
/ "EDUCATION" / "HOLIDAY" / "MEETING" / "MISCELLANEOUS"
/ "NON-WORKING HOURS" / "NOT IN OFFICE" / "PERSONAL"
/ "PHONE CALL" / "SICK DAY" / "SPECIAL OCCASION"
/ "TRAVEL" / "VACATION" / word
;Used only in "VEVENT", "VTODO" and "VJOURNAL" calendar components.

cat2value = "AUDIO" / "DISPLAY" / "EMAIL" / "PROCEDURE"
/ iana-token / x-name
;Used only in "VALARM" calendar component.

The following are examples of this property in a "VEVENT", "VTODO" or
"VJOURNAL" calendar component:

CATEGORIES:APPOINTMENT,EDUCATION

CATEGORIES:MEETING

The following are examples time zone sub-component. Some specific
requirements for the usage of this property in a "VALARM" calendar
component:

CATEGORIES:AUDIO,DISPLAY

CATEGORIES:PROCEDURE

The data type RRULE for this property is TEXT.

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4.6.4 Classification

This property purpose:

- If observance is identified by the property name CLASS. This property
defines known to have an effective end date, the access classification for a calendar component. The
property MAY only be specified in a "VEVENT", "VTODO" or "VJOURNAL"
calendar component. The property MAY only
"UNTIL" recurrence rule parameter MUST be specified once.

An access classification is only one component of used to specify the general
security system within a calendar application. It provides a method
last valid onset of capturing this observance (i.e., the scope of UNTIL date-time
will be equal to the access last instance generated by the calendar owner intends for
information within an individual calendar entry. The access
classification of an individual iCalendar component is useful when
measured along with the other security components of recurrence
pattern). It MUST be specified as a calendar
system (e.g., calendar user authentication, authorization, access
rights, access role, etc.). Hence, full DATE-TIME value, using
local time plus the semantics of UTC offset.

- The local time and UTC offset values provided in the individual
access classifications cannot "DTSTART"
property for the given observance MUST be completely defined by this memo
alone. Additionally, due to used when generating
the "blind" nature of most exchange
processes using this memo, these access classifications cannot serve
as an enforcement statement for a system receiving an iCalendar
object. Rather, they provide a method for capturing onset date-time values (instances) from the intention RRULE. This
interpretation of the calendar owner for "DTSTART" UTC offset value is specific to
"RRULE" usage in the access "VTIMEZONE" specification.

Alternatively, the "RDATE" property MAY be used to define the calendar component. The
[ICMS] provides a broader description onset
of the security system within observance by giving the individual onset date and times.
"RDATE" in this usage MUST be specified as a
calendar application. local DATE-TIME value
with UTC offset.

The optional "COMMENT" property is defined by the following notation:

class = "CLASS" ":" [WSP] classvalue CRLF

classvalue = "PUBLIC" / "PRIVATE" / "CONFIDENTIAL" / iana-token
/ x-name
;Default is PUBLIC also allowed for descriptive
explanatory text.

Example: The following are examples of the "VTIMEZONE" calendar
component:

This is an a simple example of this property:

CLASS:PUBLIC

The data type showing time zone information for the
Eastern United States using "RDATE" property. Note that this property is TEXT.

4.6.5 Comment

This property is identified by the property name COMMENT. This
property specifies non-processing information intended to provide only
suitable for a
comment to recurring event that starts on or later than April 6,
1997 at 02:00:00 EST (i.e., the calendar user. The property MAY be specified earliest effective transition date
and time) and ends no later than April 7, 1998 02:00:00 EST (i.e.,
latest valid date and time for EST in any of
the calendar components. The property MAY be specified multiple
times.

The property is defined by the following notation:

comment = "COMMENT" ":" [WSP] text CRLF

The following is an example of this property:

COMMENT:The meeting really needs to include both ourselves
and the customer. We can't hold scenario). For example,
this meeting without them can be used for a recurring event that occurs every Friday,
8am-9am, starting June 1, 1997, ending December 31, 1997.

BEGIN:VTIMEZONE
TZID:America-New_York
LAST-MODIFIED:19870101T000000Z
BEGIN:STANDARD
DTSTART:19971026T020000
RDATE:19971026T020000

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As March 6, 1998

TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19971026T020000
RDATE:19970406T020000
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE

This is a matter of fact\, the venue for simple example showing the meeting ought to be at
their site. - - John

The data type current time zone rules for this property is TEXT.

4.6.6 Contact

This property is defined by the property name CONTACT. The property
Eastern United States using a RRULE recurrence pattern. Note that
there is used no effective end date to represent contact information either of the Standard Time or alternately a reference
to contact
Daylight Time rules. This information associated with the calendar component. The
property MAY only would be specified in the "VEVENT", "VTODO" valid for a recurring
event starting today and
"VJOURNAL" calendar components. The property value consists of
textual contact information. Alternately, continuing on into the value type known future.

BEGIN:VTIMEZONE
TZID:America-New_York
LAST-MODIFIED:19870101T000000Z
TZURL:http://zones.stds_r_us.net/tz/America-New_York
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE: FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE

This is an example showing a fictitious set of rules for the
property can be reset such Eastern
United States, where the Daylight Time rule has an effective end date
(i.e., after that date, Daylight Time is no longer observed).

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DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE

This is an example showing a fictitious set of rules for the property references Eastern
United States, where the URI to first Daylight Time rule has an effective
end date. There is a second Daylight Time rule that picks up where
the contact information.

The property other left off.

BEGIN:VTIMEZONE
TZID:America-New_York
LAST-MODIFIED:19870101T000000Z
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
BEGIN:DAYLIGHT
DTSTART:19990424T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=4
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE

4.6.6 Alarm Component

Component Name: VALARM

Purpose: Provide a grouping of component properties that define an
alarm.

Formal Definition: A "VALARM" calendar component is defined by the
following notation:

contact

alarmc = "CONTACT" *(";" [WSP] parameter) "BEGIN" ":" [WSP]
text "VALARM" CRLF
(audioprop / uri dispprop / emailprop
/ procprop)
"END" ":" [WSP] "VALARM" CRLF

The following

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audioprop = alarmtype trigger [duration repeat] attach

dispprop = alarmtype description trigger [duration
repeat]

emailprop = alarmtype 1*attendee *attach description
trigger [duration repeat] summary

procprop = alarmtype attach [description] trigger [duration
repeat]

Description: A "VALARM" calendar component is an example a grouping of this property referencing textual
contact information:

CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following component
properties that is a reminder or alarm for an example of this property referencing event or a LDAP URI to-do. For
example, it may be used to define a directory entry containing the contact information:

CONTACT;VALUE=URI:ldap://host.com:6666/o=3DABC%20Industries\,
c=3DUS??(cn=3DBJim%20Dolittle)

The following is an example of this property referencing reminder for a MIME body
part containing the contact information, such as a vCard embedded in
a [MIME-DIR] content-type:

CONTACT;VALUE=URI:<part3.msg970930T083000SILVER@host.com> pending event or
an overdue to-do.

The default data "VALARM" calendar component MUST include the "ALARM-TYPE" and
"TRIGGER" properties. In addition, an AUDIO type for this of alarm MUST
include the "ATTACH" property is TEXT. The data type MAY be
reset to URI in order point to specify a reference digital sound resource to
be played. The DISPLAY type of alarm MUST include the contact
information.

4.6.7 Date/Time Completed

This property is identified by the property name COMPLETED. This
property defines "DESCRIPTION"
property. The EMAIL type of alarm MUST include the date "ATTENDEE",
"DESCRIPTION" and time that a to-do was actually
completed. "SUMMARY" properties. The PROCEDURE type of alarm
MUST include the "ATTACH" property MAY to point to a procedure resource
to be specified once in invoked.

The "VALARM" calendar component MUST only appear within either a
"VEVENT" or "VTODO" calendar component. The date and time is an UTC value. "VALARM" calendar
components cannot be nested. Multiple "VALARM" calendar components
MAY be specified.

The "TRIGGER" property is defined by specifies when the following notation:

completed = "COMPLETED" ":" [WSP] date-time CRLF alarm will be triggered.
The following is an example "TRIGGER" property specifies a duration prior to the start of this property:

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COMPLETED:19960401T235959Z an
event or a to-do. The data type for this property is DATE-TIME.

4.6.8 Date/Time Created

This property is identified by "TRIGGER" edge may be explicitly set to be
relative to the property name CREATED. This
property specifies "START" or "END" of the date and time that event or to-do with the calendar information
was created by
"RELATED" parameter of the Organizer. "TRIGGER" property. The "TRIGGER" property
value type MAY alternately be specified in any of
the set to an absolute calendar components. The property MAY only be specified once. The date and
time is an UTC of day value.

The property is defined by the following notation:

created = "CREATED" ":" [WSP] date-time CRLF

The following is

In an example alarm set to trigger on the "START" of this property:

CREATED:19960329T133000Z

The data type for this property is DATE-TIME.

4.6.9 Date/Time Due

This property is identified by an event or to-do, the
"DTSTART" property name DUE. This property
defines the date and time that a to-do is expected to be completed.
The time can either MUST be present in local time, local time with UTC offset the associated event or
UTC time. The property MAY only be specified to-do.
In an alarm in a "VTODO" "VEVENT" calendar component set to trigger on the
"END" of the event, the "DTEND" or "DTSTART" and only once. The value "DURATION"
properties MUST be present. In an alarm in a date/time after "VTODO" calendar
component set to trigger on the
DTSTART value, if specified.

The property is defined by "END" of the to-do, the following notation:

due = "DUE" ":" [WSP] date-time CRLF

The following is an example of this property:

DUE:19960401T235959Z or
"DTSTART" and "DURATION" properties MUST be present.

The type for this property is DATE-TIME.

4.6.10 Date/Time End

This property is identified by the property name DTEND. This property alarm MAY be specified within defined such that it triggers repetitively. A
definition of an alarm with a repeating trigger MUST include both the "VEVENT", "VFREEBUSY",
"DURATION" and "VTIMEZONE"
calendar components.

Within the "VEVENT" calendar component, this "REPEAT" properties. The "DURATION" property defines specifies
the end
date and time for delay period, after which the event. alarm will repeat. The "REPEAT"
property specifies the number of additional repetitions that the
alarm will triggered. This count is REQUIRED in "VEVENT"
calendar components. The time can either be in local time, local time
with UTC offset or UTC time. The local time is only in addition to the initial
triggering of the alarm. Both of these properties must be used present in
order to specify date and time values that do not need to be fixed. A
recipient MUST assume their own time zone for data and time values a repeating alarm. If one of these two properties

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that do not include time zone information. The value MUST be later in
time than March 6, 1998

are absent, then the value of alarm will not repeat beyond the "DTSTART" property.

Within initial
trigger.

The "ALARM-TYPE" property is used within the "VFREEBUSY" "VALARM" calendar component, this property defines
component to specify the
end date and time for type of the free or busy time information. alarm. The time
MUST be specified in local time "ALARM-TYPE" property
value of AUDIO specifies an alarm that triggers with UTC offset or UTC time. The an audio sound;
a value MUST be later in time than of DISPLAY specifies an alarm that triggers with the
"Calendar User Agent" displaying text; the value of EMAIL specifies
an alarm that triggers the "DTSTART" property.

The property is defined by posting of an electronic email message to
one or more email addresses; and the following notation:

dtend = "DTEND" ":" [WSP] date-time CRLF

The following is value of PROCEDURE specifies an example
alarm that triggers the execution of this property:

DTEND:19960401T235959Z a procedure. The data type for this "ALARM-TYPE"
property is DATE-TIME.

4.6.11 Date/Time Stamp

This property is identified MUST specify just one of these valid values. Multiple
categories of alarms MAY BE specified by defining more than one,
different categories of "VALARM" calendar components within a
"VEVENT" or "VTODO" calendar component.

In an AUDIO type of alarm, the "ATTACH" property name DTSTAMP. This
property specifies in the "VALARM"
calendar component MUST specify an UTC date/time stamp. The audio sound file that is intended
to be rendered as the alarm effect. If an "ATTACH" property indicates is
specified that does not refer to a digital sound resource, then no
audio alarm will be sounded. If the
date/time digital sound resource is in a
format that cannot be rendered, then no audio alarm will be sounded.

In a DISPLAY type of alarm, the iCalendar object instance was created. This "DESCRIPTION" property MUST be included in "VEVENT", "VTODO", "VJOURNAL" and
"VFREEBUSY" the
"VALARM" calendar components component is intended to permit be displayed as the recipient to know when alarm
effect. In an EMAIL category of alarm, the iCalendar object was created.

This property intended alarm effect is also useful
to protocols such as [IMIP] that have
inherent latency issues with use the delivery of content. This "DESCRIPTION" property
will assist in the proper sequencing "VALARM" calendar component
as the body text of messages containing iCalendar
objects.

This property an email message that is different than the "CREATED" and "LAST-MODIFIED"
properties. These two properties are used to specify when the
calendar service information was created and last modified. This is
different than when be sent to the iCalendar object representation of
addresses specified by any "ATTENDEE" properties present in the
"VALARM" calendar service information was created or last modified. component. The "SUMMARY" property in the "VALARM"
calendar component is defined by intended to be used as the following notation:

dtstamp = "DTSTAMP" ":" [WSP] date-time CRLF

The value type subject text for this the
email. Any "ATTACH" properties are sent as email attachments.

In a PROCEDURE type of alarm, the "ATTACH" property is DATE-TIME. The value in the "VALARM"
calendar component MUST specify a procedure or program that is
intended to be invoked as the alarm effect. If the procedure or
program is in a
UTC date/time value.

4.6.12 Date/Time Start

This format that cannot be rendered, then no procedure
alarm will be invoked. If the "DESCRIPTION" property is identified by present, its
value specifies the property name DTSTART. This
property MAY argument string to be specified within passed to the "VEVENT", "VTODO", "VFREEBUSY",
and "VTIMEZONE" calendar components.

Within procedure or
program. "Calendar User Agents" that receive an iCalendar object with
this category of alarm, should allow the "VEVENT" calendar component, "Calendar User" to disable
or otherwise ignore this property defines type of alarm. While a very useful alarm
capability, the
start date and time for PROCEDURE type of alarm should be treated by the event.
"Calendar User Agent" as a potential security risk.

Example: The property following example is REQUIRED in
"VEVENT" for a "VALARM" calendar components. The component
that specifies an audio alarm that will sound at a precise time can either be in local time, and
repeat 4 more times at 15 minute intervals:

BEGIN:VALARM
TRIGGER;VALUE=DATE-TIME:19970317T133000Z
REPEAT:4
DURATION:PT15M
ALARM-TYPE: AUDIO

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local time with UTC offset or UTC time. March 6, 1998

ATTACH:ftp://host.com/pub/sounds/bell-01.wav
END:VALARM

The local time following example is only to be
used to specify date and time values that do not need to be fixed. A
recipient MUST assume their own time zone for data and time values a "VALARM" calendar component that do not include time zone information. Events MAY have
specifies a start
date/time but no end date/time. In display alarm that case, the event does not take
up any time.

Within the "VFREEBUSY" calendar component, this property defines will trigger 15 minutes before the
scheduled start date and time for of the free or busy time information. The time
MUST be specified in local time with UTC offset event or UTC time.

Within the "VTIMEZONE" calendar component, this property defines due date/time of the
effective start date and time for a time zone specification. This
property is REQUIRED within "VTIMEZONE" calendar components. The time
MUST be specified as a UTC time.

The property to-do it is defined by the following notation:

dtstart = "DTSTART" *(";" [WSP] parameter) ":" [WSP] (date-time
/ date) CRLF
associated with and will repeat 2 more times at 15 minute intervals:

BEGIN:VALARM
TRIGGER:PT30M
REPEAT:2
DURATION:PT15M
ALARM-TYPE:DISPLAY
DESCRIPTION:Breakfast meeting with executive\n
team at 8:30 AM EST.
END:VALARM

The following example is for a "VALARM" calendar component that
specifies an example email alarm that will trigger 2 days before the
scheduled due date/time of this property:

DTSTART:19960401T235959-0600

The default data type for this property a to-do it is DATE-TIME. associated with. It does not
repeat. The data type
MAY be overridden email has a subject, body and attachment link.

BEGIN:VALARM
TRIGGER:P2D
ALARM-TYPE:EMAIL
ATTENDEE:MAILTO:john_doe@host.com
SUMMARY:*** REMINDER: SEND AGENDA FOR WEEKLY STAFF MEETING ***
DESCRIPTION:A draft agenda needs to be DATE.

4.6.13 Daylight

This property is identified by sent out to the property name DAYLIGHT. This
property MAY only be specified in a "VTIMEZONE" calendar component.
This property specifies whether Daylight Saving Time (i.e., value is
TRUE) or Standard Time (i.e., value is FALSE) attendees
to the weekly managers meeting (MGR-LIST). Attached is in effect a
pointer the document template for the
time zone. The default value is FALSE or Standard Time.

The property is defined by the following notation:

daylight = "DAYLIGHT" ":" [WSP] boolean CRLF
;Default value is FALSE agenda file.
ATTACH:http://host.com/templates/agenda.doc
END:VALARM

The following is an example of this property:

DAYLIGHT:TRUE ;Specifies DST in effect in time zone

The data type for this property is BOOLEAN.

4.6.14 Description

This property is identified by the property name DESCRIPTION. This
property provides for a more complete description of the "VALARM" calendar
component, than component that provided by the "SUMMARY" property.
specifies a procedural alarm that will trigger at a precise date/time
and will repeat 23 more times at one hour intervals. The property
MAY alarm will
invoke a procedure file.

BEGIN:VALARM
TRIGGER;VALUE=DATE-TIME:19980101T050000Z
REPEAT:23
DURATION:PT1H
ALARM-TYPE:PROCEDURE
ATTACH:ftp://host.com/novo-procs/felizano.exe
END:VALARM

4.7 Calendar Properties

The Calendar Properties are attributes that apply to the iCalendar
object, as a whole. These properties do not appear within a calendar
component. They should be specified in after the "VEVENT", "VTODO" "BEGIN:VCALENDAR"
property and "VJOURNAL" prior to any calendar component.

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4.7.1 Calendar Scale

Property Name: CALSCALE

Purpose: This property defines the calendar scale used for the
calendar information specified in the iCalendar object.

Value Type: TEXT

Conformance: Property MAY be specified multiple times only within
a "VJOURNAL" in an iCalendar object. The
default value is "GREGORIAN".

Description: This memo is based on the Gregorian calendar component. scale. The
Gregorian calendar scale is assumed if this property is not specified
in the iCalendar object. It is expected that other calendar scales
will be defined in other specifications or by future versions of this
memo.

No property parameters MAY be specified on this property.

Format Definition: The property is defined by the following notation:

description

calscale = "DESCRIPTION" *(";" [WSP] parameter) "CALSCALE" ":" [WSP]
text calvalue CRLF

calvalue = "GREGORIAN" / iana-token

Example: The following is an example of the this property:

CALSCALE:GREGORIAN

4.7.2 Method

Property Name: METHOD

Purpose: This property with formatted line
breaks in defines the property value:

DESCRIPTION:Meeting to provide technical review for "Phoenix"
design.\n Happy Face Conference Room. Phoenix design team
MUST attend this meeting.\n RSVP to team leader. iCalendar object method associated
with the calendar object.

Value Type: TEXT

Conformance: The following is property MAY be specified in an example iCalendar object.

Description: When used in a MIME message entity, the value of this
property MUST be the same as the Content-Type "method" parameter
value. This property with folding of long
lines:

DESCRIPTION:Last draft of can only appear once within the new novel is to be completed
for iCalendar
object. If either the editor's proof today.

The data type for this "METHOD" property or the Content-Type "method"
parameter is TEXT.

4.6.15 Duration specified, then the other must also be specified.

No methods are defined by this specification. This property is identified by the property name DURATION. The
property specifies a duration subject of time. The
other specifications, such as the iCalendar Transport-independent
Interoperability Protocol (iTIP) defined by [ITIP].

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If this property is not present in the iCalendar object, then no
scheduling transaction MAY be specified
in a "VEVENT" calendar component in order assumed. In such cases, the iCalendar
object is merely being used to specify transport a duration snapshot of some calendar
information; without the event, instead intention of an explicit end date/time. The conveying a scheduling
semantic.

No property parameters MAY be specified in on this property.

Format Definition: The property is defined by the following notation:

method = "METHOD" ":" [WSP] method-value CRLF

method-value = iana-token

Example: The following is a "VTODO" calendar component in order hypothetical example of this property to specify
convey that the iCalendar object is a
duration request for the to-do. a meeting:

METHOD:REQUEST

4.7.3 Product Identifier

Property Name: PRODID

Purpose: This property specifies the identifier for the product that
created the iCalendar object.

Value Type: TEXT

Conformance: The property MAY MUST be specified in an iCalendar object
but can only appear once.

Description: The vendor of the implementation should assure that this
is a
"VFREEBUSY" calendar component globally unique identifier; using some technique such as an ISO
9070 FPI value.

This property should not be used to alter the interpretation of an
iCalendar object beyond the semantics specified in order this memo. For
example, it is not to specify be used to further the amount understanding of free
time being requested. The non-
standard properties.

No property parameters MAY be specified in an "VALARM"
calendar component in order to specify the period between repeating
alarms. on this property.

Format Definition: The property is defined by the following notation:

duration

prodid = "DURATION" "PRODID" ":" [WSP] duration pidvalue CRLF

The following is an example of this property

pidvalue = text
;Any text that specifies an
interval of time of 1 hour and zero minutes describes the product and zero seconds:

DURATION:PT1H0M0S version
;and that is generally assured of being unique.

Example: The following is an example of this property that specifies an
interval of time of 15 minutes.

DURATION:PT15M

The data type for this property is DURATION. property:

PRODID:-//ABC Corporation//NONSGML My Product//EN

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4.6.16 Exception Date/Times March 6, 1998

4.7.4 Version

Property Name: VERSION

Purpose: This property specifies the identifier corresponding to the
highest version number or the minimum and maximum range of the
iCalendar specification that is identified by required in order to interpret the property name EXDATE.
iCalendar object.

Value Type: TEXT

Conformance: This property defines the list of date/time exceptions for a recurring
"VEVENT", "VTODO" or "VJOURNAL" calendar component. The times can
either MUST be specified by in local time, local time with UTC offset or UTC time.

The exception dates, if specified, is used in computing the
recurrence set. The recurrence set is the complete set of recurrence
instances for a calendar component. The recurrence set is generated
by considering the initial "DTSTART" property along with the "RRULE",
"RDATE", "EXDATE" and "EXRULE" properties contained within the an iCalendar object. The "DTSTART" property defines the first instance
in the recurrence set. Multiple instances of the "RRULE" and "EXRULE"
properties
object, but MAY also only be specified to define more sophisticated
recurrence sets. The final recurrence set is generated by gathering
all of the start date-times generated by any of the specified "RRULE"
and "RDATE" properties, and excluding any start date and times which
fall within the union once.

Description: A value of start date and times generated by any
specified "EXRULE" and "EXDATE" properties. This implies that start
date and times within exclusion related properties (i.e., "EXDATE"
and "EXRULE") take precedence over those specified by inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
generated by the "RRULE" and "RDATE" properties, only one recurrence
is considered. Duplicate instances are ignored.

The "EXDATE" "2.0" corresponds to this memo.

No property parameters MAY be used to exclude the value specified in
"DTSTART". However, in such cases the original "DTSTART" date MUST
still be maintained by the calendaring and scheduling system because
the original "DTSTART" value has inherent usage dependencies by other
properties such as the "RECURRENCE-ID". on this property.

Format Definition: The property is defined by the following notation:

exdate

version = "EXDATE" *(";" [WSP] parameter) "VERSION" ":" [WSP] [date-time /
date] *("," [WSP] date-time/date) vervalue CRLF
;Values MUST match the specified value type.

vervalue = "2.0" ;This memo
/ maxver
/ (minver ";" [WSP] maxver)

minver = <A IANA registered iCalendar version identifier>
;Minimum iCalendar version used to create the iCalendar object

maxver = <A IANA registered iCalendar version identifier>
;Maximum iCalendar version used to create the iCalendar object

Example: The following is an example of this property:

EXDATE:19960402T010000Z,19960403T010000Z,19960404T010000Z

VERSION:2.0

4.8 Component Properties

The data following properties MAY appear within calendar components, as
specified by each component property definition.

4.8.1 Descriptive Component Properties

The following properties specify descriptive information about
calendar components.

4.8.1.1 Attachment

Property Name: ATTACH

Purpose: The property provides the capability to associate a document
object with a calendar component.

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Value Type: The default value type for this property is DATE-TIME. URI. The data
value type MAY also be reset to DATE.

4.6.17 Exception Rule BINARY in order to include inline
binary encoded content information.

Conformance: The property MAY be specified in an iCalendar object.

Description: The property MAY only be specified within "VEVENT",
"VTODO", "VJOURNAL", or "VALARM" calendar components. This property
MAY be specified multiple times within an iCalendar object.

Only the "ENCODING" and "VALUE", property parameters MAY be specified
on this property.

Format Definition: The property is identified defined by the property name EXRULE. following notation:

attach = ("ATTACH" ":" [WSP] uri CRLF)

attach =/ ("ATTACH" ";" [WSP] "ENCODING" "=" "b" ";" [WSP]
"VALUE" "=" "text" ":" [WSP] binary

Example: The following are examples of this property:

ATTACH:CID:jsmith.part3.960817T083000.xyzMail@host1.com

ATTACH:FTP://xyzCorp.com/pub/reports/r-960812.ps

4.8.1.2 Categories

Property Name: CATEGORIES

Purpose: This property defines a rule or repeating pattern the categories for an exception to a
recurrence set. This calendar
component.

Value Type: TEXT

Conformance: The property MAY only be specified in the within "VEVENT",
"VTODO" or "VJOURNAL" calendar components.

The exception rule, if specified,

Description: This property is used in computing to specify categories or subtypes
of the recurrence
set. calendar component. The recurrence set is the complete set of recurrence instances

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a calendar component. The recurrence set is generated by
considering the initial "DTSTART" property along with the "RRULE",
"RDATE", "EXDATE" and "EXRULE" properties contained within the
iCalendar object. The "DTSTART" defines the first instance in the
recurrence set. Multiple instances component of the "RRULE" a particular type and "EXRULE"
properties category. Within the
"VEVENT", "VTODO" or "VJOURNAL" calendar components, more than one
category MAY also be specified to define more sophisticated
recurrence sets. The final recurrence set is generated by gathering
all as a list of the start date-times generated categories separated by any of the specified "RRULE"
and "RDATE" properties, and excluding any start date and times which
fall within the union of start date and times generated by any
specified "EXRULE" and "EXDATE" properties. This implies that start
date and times within exclusion related properties (i.e., "EXDATE"
and "EXRULE") take precedence over those specified by inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
generated by
COMMA character (ASCII decimal 44).

Only the "RRULE" and "RDATE" properties, only one recurrence
is considered. Duplicate instances are ignored.

The "EXRULE" "LANGUAGE" property parameters MAY be used to exclude the value specified in
"DTSTART". However, in such cases the original "DTSTART" date MUST
still be maintained by the calendaring and scheduling system because
the original "DTSTART" value has inherent usage dependencies by other
properties such as the "RECURRENCE-ID". on this
property.

Format Definition: The property is defined by the following notation:

exrule

categories = "EXRULE" "CATEGORIES" [catparam] ":" [WSP] recur catvalue CRLF

The following are examples of this property. Except every other week,
on Tuesday and Thursday for 4 occurrences:

EXRULE:FREQ=WEEKLY;COUNT=4;INTERVAL=2;BYDAY=TU,TH

Except daily for 10 occurrences:

EXRULE:FREQ=DAILY;COUNT=10

Except yearly

catparam = ";" [WSP] languageparm

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catvalue = "ANNIVERSARY" / "APPOINTMENT" / "BUSINESS"
/ "EDUCATION" / "HOLIDAY" / "MEETING" / "MISCELLANEOUS"
/ "NON-WORKING HOURS" / "NOT IN OFFICE" / "PERSONAL"
/ "PHONE CALL" / "SICK DAY" / "SPECIAL OCCASION"
/ "TRAVEL" / "VACATION" / text
;These are just examples
;Used only in June "VEVENT", "VTODO" and July for 8 occurrences:

EXRULE:FREQ=YEARLY;COUNT=8;BYMONTH=6,7 "VJOURNAL" calendar components.

Example: The data type for following are examples of this property is RECUR.

4.6.18 Free/Busy Time property:

CATEGORIES:APPOINTMENT,EDUCATION

CATEGORIES:MEETING

4.8.1.3 Classification

Property Name: CLASS

Purpose: This property is identified by defines the property name FREEBUSY. access classification for a
calendar component.

Value Type: TEXT

Conformance: The property defines one or more free or busy time intervals. These time
periods MAY only be specified as either a start and end date-time or in a
start date-time and duration.

The date and time is either local time with UTC offset "VEVENT",
"VTODO" or a UTC
value. "VJOURNAL" calendar components. The "FREEBUSY" property MAY include the "TYPE" property parameter to
specify whether only be
specified once.

Description: An access classification is only one component of the information defines
general security system within a free or busy time interval.

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The default "TYPE" property parameter value is BUSY. The property MAY
also include calendar application. It provides a
method of capturing the "STATUS" property parameter to provide added
information about scope of the busy time. For example, if access the busy time is
associated with a time interval that would calendar owner
intends for information within an individual calendar entry. The
access classification of an individual iCalendar component is useful
when measured along with the other security components of a calendar
system (e.g., calendar user authentication, authorization, access
rights, access role, etc.). Hence, the semantics of the individual
access classifications cannot be unavailable completely defined by this memo
alone. Additionally, due to the "blind" nature of most exchange
processes using this memo, these access classifications cannot serve
as an enforcement statement for
scheduling - - in any case - - or busy time that has been tentatively
scheduled. a system receiving an iCalendar
object. Rather, they provide a method for capturing the intention of
the calendar owner for the access to the calendar component. The default "STATUS"
[ICMS] provides a broader description of the security system within a
calendar application.

No property parameter value is BUSY. parameters MAY be specified on this property.

Format Definition: The property is defined by the following notation:

freebusy

class = "FREEBUSY" *(";" [WSP] parameter) [";" [WSP]
fbparmlist] "CLASS" ":" [WSP] fbvalue classvalue CRLF

fbparmlist = fbparam *(";" [WSP] fbparam)

fbparam

classvalue = fbtype "PUBLIC" / fbstatus

fbtype = "TYPE" "=" ("FREE" or "BUSY")
;Default is BUSY

fbstatus = "STATUS" "="
"BUSY" ;Represents busy time interval. "PRIVATE" / "UNAVAILABLE" ;Represents busy, but unavailable
;interval for cheduling; such as
;out-of-office or non-working hours. "CONFIDENTIAL" / "TENTATIVE" ;Represents busy, but tentatively
;scheduled interval. iana-token
/ x-name
;Default is BUSY

fbvalue = period *["," [WSP] period]
;Value MUST match default or explicit data type PUBLIC

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Example: The following are some examples is an example of this property:

FREEBUSY;STATUS=UNAVAILABLE:19970308T160000Z/PT8H30M

FREEBUSY;TYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H

"FREEBUSY" properties within the "VFREEBUSY" calendar component
should

CLASS:PUBLIC

4.8.1.4 Comment

Property Name: COMMENT

Purpose: This property specifies non-processing information intended
to provide a comment to the calendar user.

Value Type: TEXT

Conformance: This property may be sorted specified in ascending order, based on start time and then end
time, with the earliest periods first. an iCalendar object.

Description: The "FREEBUSY" property MAY specify more than one value, separated by be specified multiple times.

Only the COMMA character (ASCII decimal 44). In such cases, "ALTREP" or "LANGUAGE" property parameters MAY be specified
on this property.

Format Definition: The property is defined by the "FREEBUSY" following notation:

The property values should all MAY be specified in any of the same "STATUS" property parameter
type (e.g., all values calendar components.
comment = "COMMENT" [commparam] ":" [WSP] text CRLF

commparam = [";" [WSP] altrepparm ] [";" [WSP] languageparm]

Example: The following is an example of this property:

COMMENT:The meeting really needs to include both ourselves
and the customer. We can't hold this meeting without them
As a particular "STATUS" listed together in a
single property). matter of fact\, the venue for the meeting ought to be at
their site. - - John

The data type for this property is PERIOD.

4.6.19 Geographic Position TEXT.

4.8.1.5 Description

Property Name: DESCRIPTION

Purpose: This property is identified provides a more complete description of the
calendar component, than that provided by the "SUMMARY" property.

Value Type: TEXT

Conformance: The property name GEO. This property
specifies information related to MAY be specified in the global position for a "VEVENT"
or "VEVENT", "VTODO"
and "VJOURNAL" calendar component. components. The property value specifies latitude
and longitude, in that order (i.e., "LAT LON" ordering). MAY be specified
multiple times only within a "VJOURNAL" calendar component. The

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longitude represents the location east and be specified in "VALARM" calendar component.

Description: This property is used in the "VEVENT" and "VTODO" to
capture lengthy textual decriptions associated with the activity.

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This property is used in the "VJOURNAL" calendar component to capture
one more textual journal entries.

This property is used in the "VALARM" calendar component to capture
the display text for a DISPLAY category of alarm, to capture the body
text for an EMAIL category of alarm and to capture the arguement
string for a PROCEDURE category of alarm.

Only the "ALTREP" or "LANGUAGE" property parameters MAY be specified
on this property.

Format Definition: The property is defined by the following notation:

description = "DESCRIPTION" [descparam] ":" [WSP] text CRLF

descparam = [";" [WSP] altrepparm] [";" [WSP] languageparm]

Example: The following is an example of the property with formatted
line breaks in the property value:

DESCRIPTION:Meeting to provide technical review for "Phoenix"
design.\n Happy Face Conference Room. Phoenix design team
MUST attend this meeting.\n RSVP to team leader.

The following is an example of the property with folding of long
lines:

DESCRIPTION:Last draft of the new novel is to be completed
for the editor's proof today.

4.8.1.6 Geographic Position

Property Name: GEO

Purpose: This property specifies information related to the global
position for the activity specified by a calendar component.

Value Type: Two FLOAT values.

Conformance: This property MAY be specified in an iCalendar object.

Description: The property value specifies latitude and longitude, in
that order (i.e., "LAT LON" ordering). The longitude represents the
location east and west of the prime meridian as a positive or
negative real number, respectively. The latitude represents the
location north and south of the equator as a positive or negative
real number, respectively. The longitude and latitude values MUST be
specified as decimal degrees and should be specified to six decimal
places. This will allow for granularity within a meter of the
geographical position. The simple formula for converting
degrees-minutes-seconds degrees-
minutes-seconds into decimal degrees is:

decimal = degrees + minutes/60 + seconds/3600.

The property is defined by the following notation:

geo = "GEO" ":"

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No property parameters MAY be specified on this property.

Format Definition: The property is defined by the following notation:

geo = "GEO" ":" [WSP] geovalue CRLF

geovalue = float ";" [WSP] float
;Latitude and Longitude components

Example: The following is an example of this property:

GEO:37.386013;-122.082932

The default data type for this property is FLOAT.

4.6.20 Last Modified

This property is identified by the property name LAST-MODIFIED.

4.8.1.7 Location

Property Name: LOCATION

Purpose: The property specifies defines the date and time that intended venue for the activity
defined by a calendar information
was last revised. component.

Value Type: TEXT

Conformance: This property MAY be specified in the "VEVENT",
"VTODO", "VJOURNAL" "VEVENT" or "VFREEBUSY"
"VTODO" calendar components. The data and
time MUST component.

Description: Specific venues such as conference or meeting rooms may
be a UTC value.

The property is defined by the following notation:

last-mod = "LAST-MODIFIED" ":" [WSP] date-time CRLF

The following is are examples of this property:

LAST-MODIFIED:19960817T133000Z

The data type for explicitly specified using this property is DATE-TIME.

4.6.21 Location

This property property. An alternate
representation may be specified that is identified by a URI that points to
directory information with more structured specification of the property name LOCATION. The
property defines
location. For example, the intended location alternate representation may specify
either an LDAP URI pointing to an LDAP server entry or a CID URI
pointing to a MIME body part containing a vCard for the "VEVENT" location.

Only the "ALTREP" or "VTODO"
calendar component. The "LANGUAGE" property parameters MAY only be specified within a
"VEVENT" or "VTODO" calendar component.
on this property.

Format Definition: The property is defined by the following notation:

location = "LOCATION *(";" [WSP] parameter) [locparam] ":" [WSP] locavalue text CRLF

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locavalue

locparam = text / uri ;The value MUST be the same type as the
;default or explicit data type. [";" [WSP] altrepparm] [";" [WSP] languageparm]

Example: The following are some examples of this property:

LOCATION:Conference Room - F123, Bldg. 002

LOCATION;VALUE=URI:http://www.xyzcorp.com/~jsmith.vcf

The default data type for this property is TEXT. The data type MAY be
reset to URI. In the case of the data type being URI, the property
value MAY reference a vCard object. This provides a useful mechanism
to specify a location in terms of its electronic business card.

4.6.22

LOCATION;ALTREP="http://xyzcorp.com/conf-rooms/f123.vcf":
Conference Room - F123, Bldg. 002

4.8.1.8 Percent Complete

This property is identified by the property name PERCENT-COMPLETE.

Property Name: PERCENT-COMPLETE

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Purpose: This property is used by an assignee or delegatee of a to-do
to convey the percent completion of a to-do to the Organizer. The

Value Type: INTEGER

Conformance: This property MAY only be specified once and within in a "VTODO"
calendar component.

Description: The property value is an a postive integer between zero and
one hundred. A value of "0" indicates the to-do has not yet been
started. A value of "100" indicates that the to-do has been
completed. Integer values in between indicate the percent partially
complete.

When a to-do is assigned to multiple individuals, the property value
indicates the percent complete for that portion of the to-do assigned
to the assignee or delegatee. For example, if a to-do is assigned to
both individuals "A" and "B". A reply from "A" with a percent
complete of "70" indicates that "A" has completed 70% of the to-do
assigned to them. A reply from "B" with a percent complete of "50"
indicates "B" has completed 50% of the to-do assigned to them.

No property parameters MAY be specified on this property.

Format Definition: The property is defined by the following notation:

percent = "PERCENT-COMPLETE" ":" [WSP] integer CRLF

Example: The following is an example of this property to show 39%
completion:

PERCENT-COMPLETE:39

The data type for this property is INTEGER.

4.6.23

4.8.1.9 Priority

This property is identified by the property name PRIORITY.

Property Name: PRIORITY

Purpose: The property defines the relative priority for event or to-do. a calendar
component.

Value Type: INTEGER

Conformance: The property MAY only be specified within in a "VEVENT" or
"VTODO" calendar component.

Description: The value priority is specified as an integer. integer in the range
zero to nine. A value of zero (ASCII decimal 48) specifies an
undefined priority. A value of one (ASCII decimal 49) is the highest
priority. A value of two (ASCII decimal 50) is the second highest
priority. Subsequent numbers specify a decreasing ordinal priority. A
value of nine (ASCII decimal 58) is the lowest priority.

A CUA with a three-level priority scheme of "HIGH", "MEDIUM" and
"LOW" is mapped into this property such that a property value in the

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The property March 6, 1998

range of one (ASCII decimal 49) to four (ASCII decimal 52) specifies
"HIGH" priority. A value of five (ASCII decimal 53) is specified by the following notation:

priority = "PRIORITY" ":" [WSP] integer CRLF
;Default is zero

The following is an example normal or
"MEDIUM" priority. A value in the range of this property:

PRIORITY:2

The data type for this property six (ASCII decimal 54) to
nine (ASCII decimal 58) is INTEGER.

4.6.24 Recurrence Date/Times

This property "LOW" priority.

A CUA with a priority schema of "A1", "A2", "A3", "B1", "B2", ...,
"C3" is identified by the mapped into this property name RDATE. This such that a property
defines the list value of date/times for one
(ASCII decimal 49) specifies "A1", a recurrence set. The property MAY
only appear within the "VEVENT", "VTODO", "VJOURNAL" or "VTIMEZONE"
calendar components. This property MAY appear along with the "RRULE" value of two (ASCII
decimal 50) specifies "A2", a property value of three (ASCII decimal
51) specifies "A3", and so forth up to define an aggregate set a property value of repeating occurrences. When
they both appear in an iCalendar object, the recurring events 9 (ASCII
decimal 58) specifies "C3".

Other integer values are
defined by the union of occurrences defined by both reserved for future use.

Within a "VEVENT" calendar component, this property specifies a
priority for the "RDATE" and
"RRULE". The times can either event. This property may be in local time, local time with UTC
offset or UTC based time. If local time useful when more than
one event is used, the "VTIMEZONE" scheduled for a given time period.

Within a "VTODO" calendar component MUST be included in the iCalendar object,
otherwise component, this property specified a
priority for the local to-do. This property is useful in prioritizing
multiple action items for a given time value will period.

No property parameters MAY be interpreted relative to the
time zone of the recipient. specified on this property.

Format Definition: The period values for "RDATE" property
are is specified using a specific start and a specific end basic format
(period-explicit) or by the period with a specific start and a specific
duration basic format (period-start).

The recurrence dates, if specified, following
notation:

priority = "PRIORITY" ":" [WSP] privalue CRLF
;Default is used zero

privalue = integer ;Must be in computing the
recurrence set. range [0..9]
; All other values are reserved for future use

The recurrence set following is the complete set an example of recurrence
instances for a calendar component. The recurrence set is generated
by considering the initial "DTSTART" property along with the "RRULE",
"RDATE", "EXDATE" and "EXRULE" properties contained within the
iCalendar object. highest priority:

PRIORITY:1

The "DTSTART" following is an example of a property defines the first instance
in the recurrence set. Multiple instances with a next highest
priority:

PRIORITY:2

Example: The following is an example of a property with no priority.
This is equivalent to not specifying the "RRULE" and "EXRULE"
properties "PRIORITY" property.:

PRIORITY:0

4.8.1.10 Resources

Property Name: RESOURCES

Purpose: This property defines the equipment or resources anticipated
for an activity specified by a calendar entity..

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Value Type: TEXT

Conformance: This property MAY also be specified to define more sophisticated
recurrence sets. in a "VEVENT" or "VTODO"
calendar component.

Description: The final recurrence set property value is generated by gathering
all an arbitrary text. More than one
resource MAY be specified as a list of the start date-times generated resources separated by any of the specified "RRULE"
and "RDATE" properties, and excluding any start date and times which
fall within
COMMA character (ASCII decimal 44).

Only the union of start date and times generated by any
specified "EXRULE" and "EXDATE" properties. This implies that start
date and times within exclusion related properties (i.e., "EXDATE"
and "EXRULE") take precedence over those "LANGUAGE" property parameter MAY be specified by inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
generated by the "RRULE" and "RDATE" properties, only one recurrence
is considered. Duplicate instances are ignored. on this
property.

Format Definition: The property is defined by the following notation:

rdate

resources = "RDATE" *(";" [WSP] parameter) "RESOURCES" [resrcparam] ":" [WSP] rdvalue
*("," [WSP] rdvalue) resvalist CRLF

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rdvalue

resrcparam = date-time ";" [WSP] languageparm

resvalist = resvalue / date resvalue "," [WSP] resvalist

resvalue = "CATERING" / period
;Value MUST match the specified data type "CHAIRS" / "COMPUTER PROJECTOR"
/ "EASEL" / "OVERHEAD PROJECTOR" / "SPEAKER PHONE"
/ "TABLE" / "TV" / "VCR" / "VIDEO PHONE" / "VEHICLE"
/ text
;These are just examples.

Example: The following are examples is an example of this property:

RDATE:19970714T083000-0400

RDATE;VALUE=PERIOD:19960403T020000Z/19960403T040000Z,
19960404T010000Z/PT3H

RDATE;VALUE=DATE:19970101,19970120,19970217,19970421
19970526,19970704,19970901,19971014,19971128,19971129,19971225

The default data type for this property is DATE-TIME. The data type
MAY be reset to DATE or PERIOD.

4.6.25 Recurrence ID

RESOURCES:EASEL,PROJECTOR,VCR

4.8.1.11 Status

Property Name: STATUS

Purpose: This property is identified by defines the property name RECURRENCE-ID. overall status or confirmation for
the calendar component.

Value Type: TEXT

Conformance: This property is used MAY only be specified in conjunction with the "UID" property to identify a
specific instance of a recurring "VEVENT", "VTODO" or
"VTODO", "VJOURNAL" calendar component. The property value is the effective value of components.

Description: In a group scheduled calendar component, the
"DTSTART" property of the recurrence instance.

The full range of calendar components specified by a recurrence set is referenced
used by referring to just the "UID" property value
corresponding "Organizer" to provide a confirmation of the calendar component. The "RECURRENCE-ID" property
allows the reference event to an individual instance within the recurrence
set.

The time of day component for the value MUST be either an UTC or
"Attendees". For example in a
local time with UTC offset time format, unless the original "VEVENT" calendar
object was expressed as component, the
"Organizer" can indicate that a "floating" meeting is tentative, confirmed or
cancelled. In a "VTODO" calendar object; component, the "Organizer" can
indicate that an action item needs action, is completed, is in
local time with no time zone
process or being worked on, or has been cancelled. In a "VJOURNAL"
calendar component specified. If the
value of component, the "DTSTART" property is a DATE type value, then the value
MUST be the calendar date for the recurrence instance.

The date/time value is set to the time when the original recurrence
instance would occur - - meaning "Organizer" can indicate that if the intent is to change a
Friday meeting to Thursday, the date/time is still set to the
original Friday meeting.

The "RECURRENCE-ID" property journal entry
is used in conjunction with the "UID"
property to identify a particular instance of a recurring event, to-
do draft, final or journal. has been cancelled or removed.

No property parameter MAY be specified on this property.

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Format Definition: The property is defined by the following notation:

recurid

status = "RECURRENCE-ID" *(";" [WSP] parameter)
[";" [WSP] rangeparm] "STATUS" ":" [WSP] [date-time / date]
;Value must match value type.

rangeparm statvalue CRLF

statvalue = "RANGE" "=" ("THISANDPRIOR" "TENTATIVE" ;Indicates event is
;tentative.
/ "THISANDFUTURE")

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The default value "CONFIRMED" ;Indicates event is
;definite.
/ "CANCELLED" ;Indicates event was
;cancelled.
;Status values for the range parameter a "VEVENT"

statvalue =/ "NEEDS-ACTION" ;Indicates to-do needs action.
/ "COMPLETED" ;Indicates to-do completed.
/ "IN-PROCESS" ;Indicates to-do in process of
/ "CANCELLED" ;Indicates to-do was cancelled.
;Status values for "VTODO".

statvalue =/ "DRAFT" ;Indicates journal is the single recurrence
instance only. draft.
/ "FINAL" ;Indicates journal is final.
/ "CANCELLED" ;Indicates journal is removed.
;Status values for "VJOURNAL".

Example: The following are examples is an example of this property:

RECURRENCE-ID:19960401T235959Z

RECURRENCE-ID;RANGE=THISANDFUTURE:19960120T120000Z

This default data type for this property is DATE-TIME. for a "VEVENT"
calendar component:

STATUS:TENTATIVE

The data type
MAY be reset to DATE.

4.6.26 Recurrence Rule

This property following is identified by the an example of this property name RRULE. for a "VTODO" calendar
component:

STATUS:NEEDS-ACTION

The following is an example of this property for a "VJOURNAL"
calendar component:

STATUS:DRAFT

4.8.1.12 Summary

Property Name: SUMMARY

Purpose: This property defines a rule short summary or repeating pattern subject for a recurring events, to-dos,
or time zone definitions. the
calendar component.

Value Type: TEXT

Conformance: The property MAY MUST be specified in the "VEVENT", "VTODO", "VTODO"
and "VJOURNAL" or "VTIMEZONE" calendar components. The
data type for this property is RECUR.

The recurring rule, if specified, is used In addition, it MAY appear in computing the recurrence
set. The recurrence set is the complete set of recurrence instances
for a
"VALARM" calendar component. The recurrence set is generated by
considering the initial "DTSTART"

Description: This property along with is used in the "RRULE",
"RDATE", "EXDATE" "VEVENT", "VTODO" and "EXRULE" properties contained within
"VJOURNAL" calendar components to capture a short, one line summary
about the
iCalendar object. The "DTSTART" activity or journal entry.

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This property defines the first instance is used in the recurrence set. Multiple instances "VALARM" calendar component to capture
the subject of an EMAIL category of alarm.

Only the "RRULE" "ALTREP" and "EXRULE"
properties "LANGUAGE" property parameters MAY also be specified to define more sophisticated
recurrence sets.
on this property.

Format Definition: The final recurrence set property is generated defined by gathering
all of the start date-times generated by any following notation:

summary = "SUMMARY" [summparam] ":" [WSP] text CRLF

summparam = [";" [WSP] altrepparm] [";" [WSP] languageparm]

Example: The following is an example of the specified "RRULE"
and "RDATE" properties, this property:

SUMMARY:Department Party

4.8.2 Date and excluding any start Time Component Properties

The following properties specify date and times which
fall within time related information in
calendar components.

4.8.2.1 Date/Time Completed

Property Name: COMPLETED

Purpose: This property defines the union of start date and times generated by any
specified "EXRULE" and "EXDATE" properties. This implies time that start
date and times within exclusion related properties (i.e., "EXDATE"
and "EXRULE") take precedence over those specified by inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
generated by the "RRULE" and "RDATE" properties, only one recurrence
is considered. Duplicate instances are ignored. a to-do was
actually completed.

Value Type: DATE-TIME

Conformance: The "DTSTART" and "DTEND" property pair or "DTSTART" and "DURATION" property pair, specified within the iCalendar object defines the
first instance of the recurrence. When used with a recurrence rule,
the "DTSTART" and "DTEND" properties MUST MAY only be specified in local time
and the appropriate set of "VTIMEZONE" calendar components MUST be
included. For detail on the usage of the "VTIMEZONE" calendar
component, see the "VTIMEZONE" calendar a "VTODO"
component definition.

Any duration associated with the in an iCalendar object applies to all
members of the generated recurrence. Any modified duration for
specific recurrences would have to object.

Description: The date and time must be in a UTC format.

No property parameters MAY be explicitly specified using the
"RDATE" on this property.

This

Format Definition: The property is defined by the following notation:

completed = "COMPLETED" ":" [WSP] date-time CRLF

Example: The following is an example of this property:

COMPLETED:19960401T235959Z

4.8.2.2 Date/Time End

Property Name: DTEND

Purpose: This property specifies the date and time that a calendar
component ends.

Value Type: The default value type is DATE-TIME. The value type MAY
BE reset to a DATE value type.

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rrule = "RRULE" ":" [WSP] recur CRLF

Examples of this March 6, 1998

Conformance: This property include the following. All examples assume MAY only be specified within the Eastern United States "VEVENT",
"VFREEBUSY", and "VTIMEZONE" calendar components.

Description: Within the "VEVENT" calendar component, this property
defines the date and time zone.

Daily for 10 occurrences:

DTSTART:19970902T090000-0400
RRULE:FREQ=DAILY;COUNT=10

==> (1997 9AM EDT)September 2-11

Daily until 12/24/97:

DTSTART:19970902T090000-0400
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z

==> (1997 9AM EDT)September 2-30;October 1-25
(1997 9AM EST)October 26-31;November 1-30;December 1-23

Every other day - forever:

DTSTART:19970902T090000-0400
RRULE:FREQ=DAILY;INTERVAL=2
==> (1997 9AM EDT)September2,4,6,8...24,26,28,30;
October 2,4,6...20,22,24
(1997 9AM EST)October 26,28,30;November 1,3,5,7...25,27,29;
Dec 1,3,...

Every 10 days, 5 occurrences:

DTSTART:19970902T090000-0400
RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5

==> (1997 9AM EDT)September 2,12,22;October 2,12

Everyday by which the event ends. The value MUST be
later in January, for 3 years:

DTSTART:19980101T090000-0400
RRULE:FREQ=YEARLY;UNTIL:20000131T090000-0400;BYMONTH=1;BYDAY=SU,
MO,TU,WE,TH,FR,SA
or
RRULE:FREQ=DAILY;UNTIL:20000131T090000-0400;BYMONTH=1

==> (1998 9AM EDT)January 1-31
(1999 9AM EDT)January 1-31
(2000 9AM EDT)January 1-31

Weekly for 10 occurrences

DTSTART:19970902T090000-0400
RRULE:FREQ=WEEKLY;COUNT=10

==> (1997 9AM EDT)September 2,9,16,23,30;October 7,14,21

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(1997 9AM EST)October 28;November 4

Weekly until 12/24/94

DTSTART:19970902T090000-0400
RRULE:FREQ=WEEKLY;UNTIL=19971224T000000Z

==> (1997 9AM EDT)September 2,9,16,23,30;October 7,14,21
(1997 9AM EST)October 28;November 4,11,18,25;
December 2,9,16,23

Every other week - forever:

DTSTART:19970902T090000-0400
RRULE:FREQ=WEEKLY;INTERVAL=2;WKST=SU

==> (1997 9AM EDT)September 2,16,30;October 14
(1997 9AM EST)October 28;November 11,25;December 9,23
(1998 9AM EST)January 6,20;February
...

Weekly on Tuesday time than the value of the "DTSTART" property.

Within the "VFREEBUSY" calendar component, this property defines the
end date and Thursday time for 5 weeks:

DTSTART:19970902T090000-0400
RRULE:FREQ=WEEKLY;UNTIL=19971007T000000-0400;WKST=SU;BYDAY=TU,TH the free or
RRULE:FREQ=WEEKLY;COUNT=10;WKST=SU;BYDAY=TU,TH

==> (1997 9AM EDT)September 2,4,9,11,16,18,23,25,30;October 2

Every other week on Monday, Wednesday busy time information. The time
MUST be specified as in the UTC time format. The value MUST be later
in time than the value of the "DTSTART" property.

Only the "VALUE" and Friday until 12/24/97, but
starting on Tuesday, 9/2/97:

DTSTART:19970902T090000-0400
RRULE:FREQ=WEEKLY;INTERVAL=2;UNTIL=19971224T000000-0400;WKST=SU;
BYDAY=MO,WE,FR
==> (1997 9AM EDT)September 2,3,5,15,17,19,29;October 1,3,13,15,17
(1997 9AM EST)October 27,29,31;November 10,12,14,24,26,28;
December 8,10,12,22

Every other week "TZID" property parameters MAY be specified on Tuesday
this property. The "TZID" property parameter MAY only be specified
when the value type is DATE-TIME.

Format Definition: The property is defined by the following notation:

dtend = "DTEND" [dtendparam]":" [WSP] dtendval CRLF

dtendparam = [";" [WSP] "VALUE" "=" "DATE-TIME"]
[";" [WSP] "TZID" "=" paramtext

dtendparam =/ ";" [WSP] "VALUE" "=" "DATE"

dtendval = date-time / date
;Value MUST match value type

Example: The following is an example of this property:

DTEND:19960401T235959Z

DTEND;VALUE=DATE:19980704

4.8.2.3 Date/Time Due

Property Name: DUE

Purpose: This property defines the date and Thursday, for 8 occurrences:

DTSTART:19970902T090000-0400
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH

==> (1997 9AM EDT)September 2,4,16,18,30;October 2,14,16

Monthly time that a to-do is
expected to be completed.

Value Type: The default value type is DATE-TIME. The value type MAY
BE reset to a DATE value type.

Conformance: The property MAY only be specified in a "VTODO" calendar
component and only once.

Description: The value MUST be a date/time equal to or after the
DTSTART value, if specified.

Only the "VALUE" and "TZID" property parameters MAY be specified on
this property. The "TZID" property parameter MAY only be specified
when the 1st Friday for ten occurrences:

DTSTART:19970905T090000-0400
RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR

==> (1997 9AM EDT)September 5;October 3 value type is DATE-TIME.

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(1997 9AM EST)November 7;Dec 5
(1998 9AM EST)January 2;February 6;March 6;April 3
(1998 9AM EDT)MAY 1;June 5

Monthly on the 1st Friday until 12/24/94:

DTSTART:19970905T090000-0400
RRULE:FREQ=MONTHLY;UNTIL=19971224T000000Z;BYDAY=1FR

==> (1997 9AM EDT)September 5;October 3
(1997 9AM EST)November 7;December 5

Every other month on the 1st and last Sunday of March 6, 1998

Format Definition: The property is defined by the month for 10
occurrences:

DTSTART:19970907T090000-0400
RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;BYDAY=1SU,-1SU

==> (1997 9AM EDT)September 7,28
(1997 9AM EST)November 2,30
(1998 9AM EST)January 4,25;March 1,29
(1998 9AM EDT)MAY 3,31

Monthly on following notation:

due = "DUE" [dueparam]":" [WSP] dueval CRLF

dueparam = [";" [WSP] "VALUE" "=" "DATE-TIME"]
[";" [WSP] "TZID" "=" paramtext

dueparam =/ ";" [WSP] "VALUE" "=" "DATE"

dueval = date-time / date
;Value MUST match value type

Example: The following is an example of this property:

DUE:19960401T235959Z

4.8.2.4 Date/Time Start

Property Name: DTSTART

Purpose: This property specifies when the second to last Monday calendar component begins.

Value Type: The default value type is DATE-TIME. The DATE-TYPE value
will be one of the month forms defined for 6 months:

DTSTART:19970922T090000-0400
RRULE:FREQ=MONTHLY;COUNT=6;BYDAY=-2MO

==> (1997 9AM EDT)September 22;October 20
(1997 9AM EST)November 17;December 22
(1998 9AM EST)January 19;February 16

Monthly on the third DATE-TIME value type. The
value type MAY BE reset to a DATE value type.

Conformance: This property MAY be specified within the last day of "VEVENT",
"VTODO", "VFREEBUSY", and "VTIMEZONE" calendar components.

Description: Within the month, forever:

DTSTART:19970928T090000-0400
RRULE:FREQ=MONTHLY;BYMONTHDAY=-3

==> (1997 9AM EDT)September 28
(1997 9AM EST)October 29;November 28;December 29
(1998 9AM EST)January 29;February 26
...

Monthly on "VEVENT" calendar component, this property
defines the 2nd start date and 15th of the month time for 10 occurrences:

DTSTART:19970902T090000-0400
RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=2,15

==> (1997 9AM EDT)September 2,15;October 2,15
(1997 9AM EST)November 2,15;December 2,15
(1998 9AM EST)January 2,15

Monthly on the first and last day of event. The property is
REQUIRED in "VEVENT" calendar components. Events MAY have a start
date/time but no end date/time. In that case, the month event does not take
up any time.

Within the "VFREEBUSY" calendar component, this property defines the
start date and time for 10 occurrences:

DTSTART:19970930T090000-0400

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RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=1,-1

==> (1997 9AM EDT)September 30;October 1
(1997 9AM EST)October 31;November 1,30;December 1,31
(1998 9AM EST)January 1,31;February 1

Every 18 months on the 10th thru 15th of the month for 10
occurrences:

DTSTART:19970910T090000-0400
RRULE:FREQ=MONTHLY;INTERVAL=18;COUNT=10;BYMONTHDAY=10,11,12,13,14,
15

==> (1997 9AM EDT)September 10,11,12,13,14,15
(1999 9AM EST)March 10,11,12,13

Every Tuesday, every other month:

DTSTART:19970902T090000-0400
RRULE:FREQ=MONTHLY;INTERVAL=2;BYDAY=TU

==> (1997 9AM EDT)September 2,9,16,23,30
(1997 9AM EST)November 4,11,18,25
(1998 9AM EST)January 6,13,20,27;March 3,10,17,24,31
...

Yearly free or busy time information. The time
MUST be specified in June UTC time.

Within the "VTIMEZONE" calendar component, this property defines the
effective start date and July time for 10 occurrences:

DTSTART:19970610T090000-0400
RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7

==> (1997 9AM EDT)June 10;July 10
(1998 9AM EDT)June 10;July 10
(1999 9AM EDT)June 10;July 10
(2000 9AM EDT)June 10;July 10
(2001 9AM EDT)June 10;July 10
Note: Since none of a time zone specification. This
property is REQUIRED within "VTIMEZONE" calendar components. The time
MUST be specified in the BYDAY, BYMONTHDAY or BYYEARDAY components
are specified, UTC time format.

Only the day is gotten from DTSTART

Every other year on January, February, "VALUE" and March for 10 occurrences:

DTSTART:19970310T090000-0400
RRULE:FREQ=YEARLY;INTERVAL=2;COUNT=10;BYMONTH=1,2,3

==> (1997 9AM EST)March 10
(1999 9AM EST)January 10;February 10;March 10
(2001 9AM EST)January 10;February 10;March 10
(2003 9AM EST)January 10;February 10;March 10

Every 3rd year "TZID" property parameters MAY be specified on
this property. The "TZID" property parameter MAY only be specified
when the 1st, 100th and 200th day for 10 occurrences:

DTSTART:19970101T090000-0400
RRULE:FREQ=YEARLY;INTERVAL=3;COUNT=10;BYYEARDAY=1,100,200 value type is DATE-TIME.

Format Definition: The property is defined by the following notation:

dtstart = "DTSTART" [dtstparam] ":" [WSP] dtstval CRLF

dtstparam = [";" [WSP] "VALUE" "=" "DATE-TIME"]
[";" [WSP] "TZID" "=" paramtext]

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==> (1997 9AM EST)January 1
(1997 9AM EDT)April 10;July 19
(2000 9AM EST)January 1
(2000 9AM EDT)April 9;July 18
(2003 9AM EST)January 1
(2003 9AM EDT)April 10;July 19
(2006 9AM EST)January 1

Every 20th Monday March 6, 1998

dtstparam =/ ";" [WSP] "VALUE" "=" "DATE"

dtstval = date-time / date
;Value MUST match value type

Example: The following is an example of the year, forever:

DTSTART:19970519T090000-0400
RRULE:FREQ=YEARLY;BYDAY=20MO

==> (1997 9AM EDT)MAY 19
(1998 9AM EDT)MAY 18
(1999 9AM EDT)MAY 17
...

Monday this property:

DTSTART:19980118T073000Z

4.8.2.5 Duration

Property Name: DURATION

Purpose: The property specifies a duration of Week No. 20, forever:

DTSTART:19970512T090000-0400
RRULE:FREQ=YEARLY;BYWEEKNO=20;BYDAY=MO

==> (1997 9AM EDT)MAY 12
(1998 9AM EDT)MAY 11
(1999 9AM EDT)MAY 17
...

Every Thursday time .

Value Type: DURATION

Conformance: The property MAY be specified in March, forever:

DTSTART:19970313T090000-0400
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=TH

==> (1997 9AM EST)March 13,20,27
(1998 9AM EST)March 5,12,19,26
(1999 9AM EST)March 4,11,18,25
...

Every Thursday, but only during summer months, forever:

DTSTART:19970605T090000-0400
RRULE:FREQ=YEARLY;BYDAY=TH;BYMONTH=6,7,8

==> (1997 9AM EDT)June 5,12,19,26;July 3,10,17,24,31;
August 7,14,21,28
(1998 9AM EDT)June 4,11,18,25;July 2,9,16,23,30;
August 6,13,20,27
(1999 9AM EDT)June 3,10,17,24;July 1,8,15,22,29;
August 5,12,19,26
...

Every Friday a "VEVENT", "VTODO",
"VFREEBUSY" or "VALARM" calendar components.

Description: In a "VEVENT" calendar component the 13th, forever:

DTSTART:19970902T090000-0400

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EXDATE:19970902T090000-0400
RRULE:FREQ=MONTHLY;BYDAY=FR;BYMONTHDAY=13

==> (1998 9AM EST)February 13;March 13;November 13
(1999 9AM EDT)August 13
(2000 9AM EDT)October 13
...

The first Saturday that follows property may be
used to specify a duration of the first Sunday event, instead of an explicit end
date/time. In a "VTODO" calendar component the month,
forever:

DTSTART:19970913T090000-0400
RRULE:FREQ=MONTHLY;BYDAY=SA;BYMONTHDAY=7,8,9,10,11,12,13

==> (1997 9AM EDT)September 13;October 11
(1997 9AM EST)November 8;December 13
(1998 9AM EST)January 10;February 7;March 7
(1998 9AM EDT)April 11;MAY 9;June 13...
...

Every four years, the first Tuesday after property may be used
to specify a Monday in November,
forever (U.S. Presidential Election day):

DTSTART:19961105T090000-0400
RRULE:FREQ=YEARLY;INTERVAL=4;BYMONTH=11;BYDAY=TU;BYMONTHDAY=2,3,4,
5,6,7,8

==> (1996 9AM EST)November 5
(2000 9AM EST)November 7
(2004 9AM EST)November 2
...

The 3rd instance into duration for the month of one to-do, instead of Tuesday, Wednesday or
Thursday, for an explicit due
date/time. In a "VFREEBUSY" calendar component the next 3 months:

DTSTART:19970904T090000-0400
RRULE:FREQ=MONTHLY;COUNT=3;BYDAY=TU,WE,TH;BYSETPOS=3

==> (1997 9AM EDT)September 4;October 7
(1997 9AM EST)November 6

The 2nd property may be
used to last weekday specify the interval of free time being requested. In a
"VALARM" calendar component the month:

DTSTART:19970929T090000-0400
RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-2

==> (1997 9AM EDT)September 29
(1997 9AM EST)October 30;November 27;December 30
(1998 9AM EST)January 29;February 26;March 30
...

Every 3 hours from 9AM property may be used to 5PM specify the
delay period prior to repeating an alarm.

No property parameters MAY be specified on this property.

Format Definition: The property is defined by the following notation:

duration = "DURATION" ":" [WSP] duration CRLF

Example: The following is an example of this property that specifies
an interval of time of 1 hour and zero minutes and zero seconds:

DURATION:PT1H0M0S

The following is an example of this property that specifies an
interval of time of 15 minutes.

DURATION:PT15M

4.8.2.6 Free/Busy Time

Property Name: FREEBUSY

Purpose: The property defines one or more free or busy time
intervals.

Value Type: PERIOD. The data and time value MUST be in a specific day:

DTSTART:19970902T090000-0400 UTC time
format.

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RRULE:FREQ=HOURLY;INTERVAL=3;UNTIL=19970902T170000-0400

==> (September 2, 1997 EDT)09:00,12:00,15:00

Every 15 minutes for 6 occurrences:

DTSTART:19970902T090000-0400
RRULE:FREQ=MINUTELY;INTERVAL=15;COUNT=6

==> (September 2, 1997 EDT)09:00,09:15,09:30,09:45,10:00,10:15

Every hour and a half for 4 occurrences:

DTSTART:19970902T090000-0400
RRULE:FREQ=MINUTELY;INTERVAL=90;COUNT=4

==> (September 2, 1997 EDT)09:00,10:30;12:00;13:30

Every 20 minutes from 9AM to 4:40PM every day:

DTSTART:19970902T090000-0400
RRULE:FREQ=DAILY;BYHOUR=9,10,11,12,13,14,15,16;BYMINUTE=0,20,40
or
RRULE:FREQ=MINUTELY;INTERVAL=20;BYHOUR=9,10,11,12,13,14,15,16

==> (September 2, 1997 EDT)9:00,9:20,9:40,10:00,10:20,
... 16:00,16:20,16:40
(September 3 1997 EDT)9:00,9:20,9:40,10:00,10:20,
...16:00,16:20,16:40
...

An example where the days generated makes a difference because of
WKST:

DTSTART:19970805T090000-0400
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=MO

==> (1997 EDT)Aug 5,10,19,24

changing only WKST from MO to SU, yields different reults...

DTSTART:19970805T090000-0400
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=SU
==> (1997 EDT)August 5,17,19,31

4.6.27 Related To

This property is identified by the property name RELATED-TO. The
property is used to represent a relationship or reference between one
calendar component and another. March 6, 1998

Conformance: The property MAY only be specified
once in the "VEVENT", "VTODO", "VJOURNAL" or a "VFREEBUSY"
calendar
components. The property value consists of the persistent, globally
unique identifier of another calendar component. This value would

Description: These time periods MAY be
represented in specified as either a calendar component by the "UID" property.

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and end date-time or a start date-time and duration. The date and
time MUST be a UTC time format.

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By default, include the "TYPE" property value points to another calendar component
that has a PARENT relationship parameter to
specify whether the referencing object. information defines a FREE or BUSY time interval.
The
"RELTYPE" default "TYPE" property parameter value is used to either explicitly state BUSY.

If the
default PARENT relationship type "TYPE" property parameter is set to "BUSY", then the referenced calendar component
or property
MAY also include the "BSTAT" property parameter to override provide added
information about the default PARENT relationship type and specify
either a CHILD or SIBLING relationship. The PARENT relationship
indicates that busy time. For example, if the calendar component busy time is
associated with a subordinate of the
referenced calendar component. The CHILD relationship indicates time interval that would be unavailable for
scheduling in any case the calendar component is a superior of parameter MAY BE set to UNAVAILABLE or if
the referenced calendar
component. The SIBLING relationship indicates busy time that has been tentatively scheduled the calendar
component is a peer of the referenced calendar component.

Changes to a calendar component referenced by this property parameter MAY have
an implied impact
BE set to TENTATIVE. The default "BSTAT" property parameter value is
BUSY, providing no additional busy status information.

"FREEBUSY" properties within the related "VFREEBUSY" calendar component. For example, if
a group event changes its component
should be sorted in ascending order, based on start or time and then end date or
time, then with the
related, dependent events will need to have their start and end dates
changed in a corresponding way. This earliest periods first.

The "FREEBUSY" property is intended only to
provide information on MAY specify more than one value, separated by
the relationship COMMA character (ASCII decimal 44). In such cases, the "FREEBUSY"
property values should all be of calendar components. It is
up to the target calendar system to maintain any same "TYPE" and "BSTAT" property
implications
parameter type (e.g., all values of a particular "TYPE" and "BSTAT"
listed together in a single property).

No property parameters other than the property specific "TYPE" and
"BSTAT" parameters MAY be specified on this relationship. property.

Format Definition: The property is defined by the following notation:

freebusy = "RELATED-TO" "FREEBUSY" [";" [WSP] relparam) fbparmlist] ":" [WSP] uid fbvalue
CRLF

relparam

fbparmlist = "RELTYPE" "="
"PARENT" ; Parent relationship. Default.
/ "CHILD" ; Child relationship. fb-free / "SIBLING" ; Sibling relationship.

The following fb-busy

fb-free = "TYPE" "=" "FREE"

fb-busy = ["TYPE" "=" "BUSY"] [";" [WSP] fbstatus]
;Default is an example BUSY

fbstatus = "BSTAT" "="
"BUSY" ;Represents busy time interval.
/ "UNAVAILABLE" ;Represents busy, but unavailable
;interval for cheduling; such as
;out-of-office or non-working hours.
/ "TENTATIVE" ;Represents busy, but only tentatively
;scheduled interval.
/ iana-token ;Represents other registered busy status

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/ x-name ;Represents experimental busy status
;Default is BUSY

fbvalue = period *["," [WSP] period]
;Time value MUST be in the UTC time format.

Example: The following are some examples of this property:

RELATED-TO:<jsmith.part7.19960817T083000.xyzMail@host3.com>

RELATED-TO:<19960401-080045-4000F192713-0052@host1.com>

The data type for this property is UID.

4.6.28 Repeat Count

FREEBUSY;BSTAT=UNAVAILABLE:19970308T160000Z/PT8H30M

FREEBUSY;TYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H

4.8.2.7 Time Transparency

Property Name: TRANSP

Purpose: This property defines whether an event is identified by the property name REPEAT. transparent or not
to busy time searches.

Value Type: TEXT

Conformance: This property defines MAY only be specified in a "VEVENT"
calendar component.

Description: Transparency is the number of state that determines whether an
event takes up time on a calendar, and with be reflected as "busy
time", or is just "penciled in" to the alarm should calendar, and will not be repeated,
after
reflected as "busy time". If the initial trigger. event is transparent, then other
events can be scheduled in the same time period without there being a
time period conflict. If not specified, the default state is OPAQUE.

No property parameters MAY be specified on this property.

Format Definition: The property is defined specified by the following
notation:

repeatcnt

transp = "REPEAT" "TRANSP" ":" [WSP] integer transvalue CRLF

transvalue = "OPAQUE" ;Blocks or opaque on busy time searches.
/ "TRANSPARENT" ;Transparent on busy time searches.
;Default value is "0", zero. OPAQUE

Example: The following is an example of this property:

REPEAT:4

The data type for the property for an event
that is INTEGER.

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4.6.29 Request Status

This property transparent or does not block on free/busy time searches:

TRANSP:TRANSPARENT

The following is identified by the an example of this property name REQUEST-STATUS. for an event that is
opaque or blocks on free/busy time searches:

TRANSP:OPAQUE

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4.8.3 Time Zone Component Properties

The following properties specify time zone information in calendar
components.

4.8.3.1 Time Zone Identifier

Property Name: TZID

Purpose: This property defines specifies the status code returned for a scheduling request. text value that uniquely
identifies the VTIMZONE calendar component.

Value Type: TEXT

Conformance: This property MUST be specified in a "VTIMEZONE"
calendar component.

Description: This is used to return status code information related to the processing of an associated key by which a time zone object is
referenced by any iCalendar object. The properties whose data type for
this property is TEXT.

The value consists of a short return status, a longer return status
description, and optionally the offending data. either
DATE-TIME or TIME. The components presence of the
value are separated by the SEMICOLON SOLIDUS character (ASCII
decimal 59).

The short return status is 47) as a PERIOD character (ASCII decimal xx)
separated set of integers. For example, "3.1.1". The successive
levels of integers provide for prefix, indicates that this TZID represents an
unique ID in a successive level of status code
granularity.

The globally defined time zone registry (when such
registry is defined).

No property parameters MAY be specified on this property.

Format Definition: This property is defined by the following
notation:

rstatus

tzid = "REQUEST-STATUS" *(";" [WSP] parameter) "TZID" ":" [WSP]
statcode ";" [WSP] statdesc [";" [WSP] extdata]

statcode = 1*DIGIT *("." 1*DIGIT)
;Hierarchical, numeric return status code

statdesc = [tzidprefix] text
;Textual status description

extdata CRLF

tzidprefix = text
;Textual exception data. For example, the offending property
;name and value or complete property line. "/"

Example: The following are some possible examples of this property (Note: non-globally unique time zone
identifiers:

TZID:America-New_York

TZID:/US-California-Los_Angeles

The
BACKSLASH character escapement following is an example of separator characters in a globally unique time zone
identifier:

TZID:/US-New York-New_York

4.8.3.2 Time Zone Name

Property Name: TZNAME

Purpose: This property
value):

REQUEST-STATUS:2.0;Success

REQUEST-STATUS:3.1;Invalid property value;DTSTART:96-Apr-01

REQUEST-STATUS:2.8; Success\, repeating event ignored. Scheduled
as a single event.;RRULE\:FREQ=WEEKLY\;INTERVAL=2

REQUEST-STATUS:4.1;Event conflict. Date/time is busy.

REQUEST-STATUS:3.7;Invalid calendar user;ATTENDEE:
MAILTO:jsmith@host.com

The following are valid classes for specifies the return status code.
Individual iCalendar object methods will define specific return
status codes customary designation for these classes.

Value Type: TEXT

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| Status Code | |
|==============+===============================================|
| 1.xx | Preliminary success. March 6, 1998

Conformance: This class of status |
| | of status code indicates that property MAY only be specified in the request has |
| | request has been initially processed but that |
| | completion is pending. |
|==============+===============================================|
| 2.xx | Successful. "VTIMEZONE"
calendar component.

Description: This class of status code |
| | indicates that the request was completed |
| | successfuly. However, property may be specified in multiple languages; in
order to provide for different national language requirements.

Only the exact status code |
| | "LANGUAGE" property parameter MAY indicate that a fallback has been taken. |
|==============+===============================================|
| 3.xx | Client Error. be specified on this
property.

Format Definition: This class of status code |
| | indicates that the request was not successful.|
| | The error property is defined by the result of either a syntax or |
| | a semantic error in the client formatted |
| | request. Request should not be retried until |
| | the condition in the request is corrected. |
|==============+===============================================|
| 4.xx | Scheduling Error. This class of status code |
| | indicates that the request was not successful.|
| | Some sort following
notation:

tzname = "TZNAME" [tznparam] ":" [WSP] text CRLF

tznparam = ";" [WSP] languageparm

Example: The following are examples of error occurred within the |
| | calendaring and scheduling service, not |
| | directly related to the request itself. |
|==============+===============================================|

4.6.30 Resources this property:

TZNAME: EST

TZNAME;LANGUAGE=fr-CA:HNE

4.8.3.3 Time Zone Offset From

Property Name: TZOFFSETFROM

Purpose: This property is identified by specifies the offset which is in use prior to
this time zone observance.

Value Type: UTC-OFFSET

Conformance: This property name RESOURCES. MUST only be specified in a "VTIMEZONE"
calendar component. A "VTIMEZONE" calendar component MUST include
this property.

Description: This property defines the equipment or resources needed for specifies the event or
to-do. The property value offset which is an arbitrary text. The in use prior
to this time observance. It is used to calculate the absolute time at
which the transition to a given observance takes place. This property MAY
MUST only be specified in the "VEVENT" or "VTODO" a "VTIMEZONE" calendar component. More than
one resource A
"VTIMEZONE" calendar component MUST include this property. The
property value is a signed numeric indicating the number of hours and
possibly minutes from UTC. Positive numbers represents time zones
east, or ahead of UTC. Negative numbers represents time zones west
of, or behind UTC.

No property parameter MAY be specified as a list of resources separated by the
COMMA character (ASCII decimal 44). on this property.

Format Definition: The property is defined by the following notation:

resource

tzoffsetfrom = "RESOURCES" *(";" [WSP] parameter) "TZOFFSETFROM" ":" [WSP]
resvalist utc-offset CRLF

resvalist = resvalue / resvalue "," [WSP] resvalist

resvalue = "CATERING" / "CHAIRS" / "COMPUTER PROJECTOR"
/ "EASEL" / "OVERHEAD PROJECTOR" / "SPEAKER PHONE"
/ "TABLE" / "TV" / "VCR" / "VIDEO PHONE" / "VEHICLE"
/ word

Example: The following is an example are examples of this property:

RESOURCES:EASEL,PROJECTOR,VCR

The data type for this property is TEXT.

TZOFFSETFROM:-0500

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4.6.31 Sequence Number

This property is identified by the property name SEQUENCE. March 6, 1998

TZOFFSETFROM:+0530

4.8.3.4 Time Zone Offset To

Property Name: TZOFFSETTO

Purpose: This property defines the revision sequence of specifies the calendar component used offset which is in a request. The use in this
time zone observance.

Value Type: UTC-OFFSET

Conformance: This property MAY only be specified in a "VEVENT",
"VTODO", "VJOURNAL" or "VFREEBUSY" "VTIMEZONE"
calendar component. A "VTIMEZONE" calendar component MUST include
this property.

Description: This property
is needed to properly handle specifies the receipt and processing of a sequence
of calendar components that have been delivered out of order. Such offset which is in use in
this time zone observance. It is used to calculate the case absolute time
for store-and-forward based transports. the new observance. The first request property value is
created with a sequence signed numeric
indicating the number of "0" (ASCII decimal 48). It is
incremented each hours and possibly minutes from UTC.
Positive numbers represents time the ORGANIZER zones east, or OWNER issues a revision to the
request. The sequence number MUST be monotonically incremented when
one ahead of the following properties in a calendar component is changed:

. "DTSTART"
. "DTEND"
. "DUE"
. "RDATE"
. "RRULE"
. "EXDATE"
. "EXRULE" UTC.
Negative numbers represents time zones west of, or behind UTC.

No property parameter MAY be specified on this property.

Format Definition: The property is defined by the following notation:

sequence

tzoffsetto = "SEQUENCE" "TZOFFSETTO" ":" [WSP] integer utc-offset CRLF
;Default is "0".

Example: The following is an example of are examples of this property:

SEQUENCE:1

TZOFFSETTO:-0500

TZOFFSETTO:+0530

4.8.3.5 Time Zone URL

Property Name: TZURL

Purpose: The data type TZURL provides a means for this property is INTEGER.

4.6.32 Status

This property is identified by the property name STATUS. This
property defines the orignator's view a VTIMEZONE component to
point to a network location that can be used to retrieve an up-to-
date version of the overall status for the
calendar component. itself.

Value Type: URI

Conformance: This property MAY only be specified in the
"VEVENT", "VTODO", "VJOURNAL" a "VTIMEZONE"
calendar components. component.

Description: The property is TZURL provides a means for a VTIMEZONE component to
point to a network location that can be used to specify the originator's view retrieve an up-to-
date version of the general consensus for
the event or the to-do. In addition, when specified itself. This provides a hook to handle changes
government bodies impose upon timezone definitions. Retrieval of
this resource results in an iCalendar object containing a group
scheduled to-do the single
VTIMEZONE component and a METHOD property is used set to specify the originator's view
of the completion status for the to-do. The PUBLISH.

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No property parameter MAY also specify
whether the event or to-do has been cancelled. be specified on this property.

Format Definition: The property is defined by the following notation:

status

tzurl = "STATUS" "TZURL" ":" [WSP] statvalue uri CRLF

statvalue = "NEEDS-ACTION" ;Indicates to-do needs action.
/ "COMPLETED" ;Indicates to-do completed.
/ "IN-PROCESS" ;Indicates to-do in process of
;being completed.
/ "TENTATIVE" ;Indicates event or to-do is

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;tentative.
/ "CONFIRMED" ;Indicates event or to-do is
;definite.
/ "CANCELLED" ;Indicates event or to-do was
;cancelled.

Example: The following is an example of this property:

STATUS:TENTATIVE

TZURL:http://timezones.r.us.net/tz/US-California-Los_Angeles

4.8.4 Relationship Component Properties

The following properties specify relationship information in calendar
components.

4.8.4.1 Attendee

Property Name: ATTENDEE

Purpose: The data type for this property is TEXT.

4.6.33 Summary defines an attendee within a calendar
component.

Value Type: CAL-ADDRESS

Conformance: This property is identified by the property name SUMMARY. This
property defines MUST be specified in an iCalendar object
that specifies a short summary or subject for the group scheduled calendar
component. The entity. This property MUST
be specified in the "VEVENT", "VTODO"
and "VJOURNAL" calendar components. In addition, it MAY appear in the
"VALARM" calendar component.

The property is defined by the following notation:

summary = "SUMMARY" *(";" [WSP] parameter) ":" [WSP] text CRLF

The following is an example iCalendar object that specifies the publication of this property:

SUMMARY:Department Party

The data type for this property is TEXT.

4.6.34 Time Transparency
a calendar user's busy time. This property is identified by the property name TRANSP. This
property defines whether not specified in an event is transparent
iCalendar object that specifies only a time zone definition or that
defines calendar entities that are not to busy time
searches. This property MAY group scheduled entities, but
are entities only be on a single user's calendar.

Description: The property is specified in within the "VEVENT", "VTODO",
"VJOURNAL calendar components to specify participants, non-
participants and the chair of a "VEVENT" group scheduled calendar
component. entity. The
property is specified by within the following notation:

transp = "TRANSP" ":" [WSP] transvalue CRLF

transvalue = "OPAQUE" ;Blocks "VFREEBUSY" calendar component to
specify the calendar user associated with the free or opaque on busy time searches.
/ "TRANSPARENT" ;Transparent on busy time searches.

;Default value is OPAQUE time. The following
property is specified within an example "EMAIL" category of this property for the "VALARM"
calendar component to specify an event email address that is
transparent or does not block on free/busy time searches:

TRANSP:TRANSPARENT

The following is an example to receive the
email type of this iCalendar alarm.

The property has the property parameter CN, for an event that is
opaque the common or blocks
displayable name associated with the calendar address, ROLE, for the
intended role that the attendee will have in the calendar component;
ATTSTAT, for the status of the attendee's participation; RSVP, for
indicating whether the favor of a reply is requested; EXPECT, to
indicate the expectation of the attendee's participation by the
originator; MEMBER, to indicate the groups that the attendee belongs
to; DELEGATED-TO, to indicate the calendar users that the original
request was delegated to; and DELEGATED-FROM, to indicate whom the
request was delegated from; SENT-BY, to indicate whom is acting on free/busy time searches:
behalf of the ATTENDEE and DIR, to indicate the URI that points to
the directory information corresponding to the attendee. These
property parameters MAY only be specified on an "ATTENDEE" property

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TRANSP:OPAQUE

The data type for this property is TEXT.

4.6.35 Time Zone Name

This March 6, 1998

in either a "VEVENT", "VTODO" or "VJOURNAL" calendar component. They
MUST not be specified in an "ATTENDEE" property is identified in a "VFREEBUSY" or
"VALARM" calendar component.

A recipient delegated a request MUST inherit the RSVP and EXPECT
values from the attendee that delegated the request to them.

Multiple attendees MAY be specified by including multiple "ATTENDEE"
properties within the property name TZNAME. This
property specifies MIME calendaring entity.

Only the customary designation for a time zone
description. This "TYPE", "CN", "ROLE", "ATTSTAT", "RSVP", "DELEGATED-TO",
"DELEGATED-FROM", "SENT-BY" or "DIR" property specific parameters MAY only
be specified in on this property. In addition, the "VTIMEZONE"
calendar component.

This "LANGUAGE" property
parameter MAY be specified on this property.

Format Definition: The property is defined by the following notation:

tzname

attendee = "TZNAME" "ATTENDEE" *(";" [WSP] parameter) attparam) ":" [WSP] text
cal-address CRLF

The following are examples of this property:

TZNAME: EST

TZNAME: PDT

The data type for this property is TEXT.

4.6.36 Time Zone Offset

This property

attparam = typeparm / cnparm / roleparm / statusparm / rsvpparm
/ memberparm / deletoparm / delefromparm
/ sentbyparm / dirparm

typeparm = "TYPE" "="
("INDIVIDUAL" ; An individual
/ "GROUP" ; A group of individuals
/ "RESOURCE" ; A physical resource
/ "ROOM" ; A room resource
/ "UNKNOWN") ; Otherwise not known
;Default value is identified by the property name TZOFFSET. This
property specifies INDIVIDUAL

cnparm = "CN" "=" param-value

roleparm = "ROLE" "="
("CHAIR" ; Indicates CHAIR of the offset from UTC for calendar entity
/ "REQ-PARTICIPANT" ; Indicates a time zone. This property
MAY only be specified in participant whose
;participation is required
/ "OPT-PARTICIPANT" ;Indicates a "VTIMEZONE" calendar component. A
"VTIMEZONE" calendar component MUST include this property. The
property value participant whose
;participation is optional
/ "NON-PARTICIPANT" ;Indicates a signed numeric indicating the number of hours and
possibly minutes from UTC. Positive numbers represents time zones
east, participant who
;is copied for information purposes only
;Default is REQ-PARTICIPANT

statusparm = "ATTSTAT" "="
("NEEDS-ACTION" ; Indicates event or ahead of UTC. Negative numbers represents time zones west
of, to-do needs action
/ "ACCEPTED" ; Indicates event or behind UTC.

The property is defined by to-do accepted
/ "DECLINED" ; Indicates event or to-do not accepted
/ "TENTATIVE" ; Indicates event or to-do tentatively
; accepted. Status MAY change in the following notation:

tzoffset = "TZOFFSET" ":" [WSP] utc-offset CRLF

The following are examples of this property:

TZOFFSET:-0500

TZOFFSET:+0530

The data type for this property is UTC-OFFSET.

4.6.37 Uniform Resource Locator

This future.
/ "COMPLETED" ; Indicates to-do was completed.
; COMPLETED property has date/time completed.
/ "IN-PROCESS" ;Indicates to-do is identified by in the property name URL. This property
defines a Uniform Resource Locator (URL) associated with the
iCalendar object. This property MAY be specified once in the
"VEVENT", "VTODO", "VJOURNAL" and "VFREEBUSY" calendar components.

The property is defined by the following notation: process of
; being completed.

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url March 6, 1998

/ "DELEGATED" ; Indicates event or to-do delegated
; to another ATTENDEE
;Default is NEEDS-ACTION

rsvpparm = "URL" ":" "RSVP" "="
("TRUE" ; Indicates response requested
/ "FALSE") ; Indicates no response needed
;Default is FALSE

memberparm = "MEMBER" "=" DQUOTE uri DQUOTE
*("," [WSP] DQUOTE uri CRLF

The following is an example of this property:

URL:http://abc.com/pub/calendars/jsmith/mytime.or3

The data type for this property is URI.

4.6.38 Unique Identifier

This property is identified by the property name UID. This property
defines the persistent, globally unique identifier for the calendar
component. The property DQUOTE)
; Indicates a group or mailing list
; MUST be specified a MAILTO URI as defined in the "VEVENT", "VTODO",
"VJOURNAL" and "VFREEBUSY" calendar components. [RFC 1738]
; The UID itself MUST parameter value must be put in a globally unique identifier. The generator of
the identifier MUST guarantee that quoted string.

deletoparm = "DELEGATED-TO" "=" DQUOTE uri DQUOTE
*("," [WSP] DQUOTE uri DQUOTE)
; Indicates who the identifier is unique. There
are several algorithms that can be used to accomplish this. The
identifier request is RECOMMENDED delegated to
; MUST be the identical syntax to the a MAILTO URI as defined in [RFC 822]
addr-spec. A good method to assure uniqueness is to 1738]
; The parameter value must be put the domain
name or in a domain literal IP address of the host on which quoted string.delefromparm =
"DELEGATED-FROM" "=" DQUOTE uri DQUOTE
*("," [WSP]DQUOTE uri DQUOTE)
;Indicates who the
identifier was created request is delegated from
; MUST be a MAILTO URI as defined in [RFC 1738]
; The parameter value must be put in a quoted string.

sentbyparm = "SENT-BY" "=" DQUOTE uri DQUOTE
; Indicates a calendar user acting on the right hand side behalf of the "@", and on the
left hand side, attendee.
; MUST be a MAILTO URI as defined in [RFC 1738]
; The parameter value must be put in a combination of the current calendar date and
time quoted string.dirparm
= "DIR" "=" DQUOTE uri DQUOTE

Example: The following are examples of day (i.e., formatted in as this property's use for a DATE-TIME value) along to-
do:

ORGANIZER:MAILTO:jsmith@host1.com
ATTENDEE;MEMBER="MAILTO:DEV-GROUP@host2.com":
MAILTO:joecool@host2.com
ATTENDEE;DELEGATED-FROM="MAILTO:immud@host3.com":
MAILTO:ildoit@host1.com

The following is an example of this property used for specifying
multiple attendees to an event:

ORGANIZER:MAILTO:jsmith@host1.com
ATTENDEE;ROLE=REQ-PARTICIPANT;ATTSTAT=TENTATIVE;CN=Henry Cabot
:MAILTO:hcabot@host2.com
ATTENDEE;ROLE=REQ-PARTICIPANT;DELEGATED-FROM="MAILTO:bob@host.com"
;ATTSTAT=ACCEPTED;CN=Jane Doe: MAILTO:jdoe@host1.com

The following is an example of this property with some
other currently unique (perhaps sequential) identifier available on
the system (for example, a process id number). Using a date/time
value on URI to the left hand side
directory information associated with the attendee:

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ATTENDEE;CN=John Smith;DIR="ldap://host.com:6666/o=eDABC%
20Industries,c=3DUS??(cn=3DBJim%20Dolittle)":MAILTO:jimdo@
host1.com

The following is an example of this property with "delegatee" and a domain name or domain literal
"delegator" information for an event:

ORGANIZER;CN=John Smith:MAILTO:jsmith@host.com
ATTENDEE;ROLE=REQ-PARTICIPANT;ATTSTAT=TENTATIVE;DELEGATED-FROM=
"MAILTO:iamboss@host2.com";CN=Henry Cabot:MAILTO:hcabot@
host2.com
ATTENDEE;ROLE=NON-PARTICIPANT;ATTSTAT=DELEGATED;DELEGATED-TO=
"MAILTO:hcabot@host2.com";CN=The Big Cheese:MAILTO:iamboss
@host2.com
ATTENDEE;ROLE=REQ-PARTICIPANT;ATTSTAT=ACCEPTED;CN=Jane Doe
:MAILTO:jdoe@host1.com

Example: The following is an example of this property's use when
another calendar user is acting on behalf of the right hand side makes it possible "Attendee":

ATTENDEE;SENT-BY=MAILTO:jan_doe@host1.com;CN=John Smith:MAILTO:
jsmith@host1.com

4.8.4.2 Contact

Property Name: CONTACT

Purpose: The property is used to guarantee uniqueness since
no two hosts should be using the same domain name represent contact information or IP address at
the same time. Though other algorithms will work, it is RECOMMENDED
that the right hand side contain some domain identifier (either of
the host itself or otherwise) such that the generator of the message
identifier can guarantee the uniqueness of the left hand side within
the scope of that domain.

This is the method for correlating scheduling messages
alternately a reference to contact information associated with the
referenced "VEVENT", "VTODO", or "VJOURNAL"
calendar component.

Value Type: TEXT

Conformance: The full range of calendar components property MAY only be specified by in a recurrence set
is referenced by referring to just the "UID" property value
corresponding to the "VEVENT",
"VTODO" and "VJOURNAL" calendar component. component in an iCalendar object.

Description: The "RECURRENCE-ID" property
allows value consists of textual contact
information. An alternative representation for the reference property value MAY
also be specified that refers to a URI pointing to an individual instance within alternate form,
such as a vCard, for the recurrence
set. contact information.

Only the "ALTREP" or "LANGUAGE" property parameters MAY be specified
on this property.

Format Definition: The property is defined by the following notation:

uid

contact = "UID" "CONTACT" [contparam] ":" [WSP] text CRLF

contparam = [";" [WSP] altrepparm] [";" [WSP] languageparm]

Example: The following is an example of this property:

UID:19960401T080045Z-4000F192713-0052@host1.com

This property is an important method for group scheduling
applications to match requests with later replies, modifications or referencing
textual contact information:

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deletion requests. Calendaring and scheduling applications MUST
generate March 6, 1998

CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

The following is an example of this property in "VEVENT", "VTODO" and "VJOURNAL" calendar
components to assure interoperability with other group scheduling
applications. This identifier is created by the calendar system that
generates an iCalendar object.

Implementations MUST be able to receive and persist values alternate
representation of at
least 255 characters for this property. a LDAP URI to a directory entry containing the
contact information:

CONTACT;ALTREP="ldap://host.com:6666/o=3DABC%20Industries\,
c=3DUS??(cn=3DBJim%20Dolittle)":Jim Dolittle\, ABC Industries\,
+1-919-555-1234

The data type for following is an example of this property is TEXT.

4.6.39 Non-standard Properties

The with an alternate
representation of a MIME Calendaring and Scheduling Content Type provides body part containing the contact
information, such as a "standard
mechanism for doing non-standard things". This extension support vCard embedded in a [MIME-DIR] content-type:

CONTACT;ALTREP="CID=<part3.msg970930T083000SILVER@host.com>":Jim
Dolittle\, ABC Industries\, +1-919-555-1234

The following is
provided for implementers to "push the envelope" on the existing
version an example of this property referencing a network
resource, such as a vCard object containing the memo. Extension properties are specified by contact information:

CONTACT;ALTREP="http://host.com/pdi/jdoe.vcf":Jim
Dolittle\, ABC Industries\, +1-919-555-1234

4.8.4.3 Organizer

Property Name: ORGANIZER

Purpose: The property
and/or defines the organizer for a calendar component.

Value Type: CAL-ADDRESS

Conformance: This property parameter names MUST be specified in an iCalendar object
that have specifies a group scheduled calendar entity. This property MUST
be specified in an iCalendar object that specifies the prefix text publication of "X-"
(the two character sequence: LATIN CAPITAL LETTER X character
followed by the HYPEN-MINUS character). It is RECOMMENDED
a calendar user's busy time. This property MUST not be specified in
an iCalendar object that
vendors concatenate onto this sentinel another short prefix text specifies only a time zone definition or
that defines calendar entities that are not group scheduled entities,
but are entities only on a single user's calendar.

Description: The property is specified within the "VEVENT", "VTODO",
"VJOURNAL calendar components to
identify specify the vendor. This will facilitate readability organizer of a group
scheduled calendar entity. The property is specified within the
extensions and minimize possible collision of names between different
vendors. User agents that support this content type are expected to
be able
"VFREEBUSY" calendar component to parse specify the calendar user
requesting the free or busy time.

The property has the extension properties and property parameters but CN, for specifying the
common or display name associated with the "Organizer", DIR, for
specifying a pointer to the directory information associated with the
"Organizer", SENT-BY, for specifying another calendar user that is
acting on behalf of the "Organizer". No other parameters MAY ignore them. be
specified on this property.

Format Definition: The property is defined by the following notation:

extension

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organizer = "X-" [vendorid] "-" word *(";" [WSP] param) "ORGANIZER" [orgparam] ":" [WSP] value-list
cal-address CRLF
; Lines longer than 75 characters should be folded

vendorid

orgparam = 3*char ;Vendor identification prefix text [";" [WSP] "CN" "=" param-value]
[";" [WSP] "DIR" "=" DQUOTE uri DQUOTE]
proxyparam

proxyparam = (";" [WSP] "SENT-BY" "=" DQUOTE cal-address DQUOTE)

Example: The following might be the ABC vendor's extension for is an audio-clip
form example of subject this property:

X-ABC-MMSUBJ;TYPE=wave; VALUE=URI: http://load.noise.org/mysubj.wav

At present, there

ORGANIZER;CN=John Smith:MAILTO:jsmith@host1.com

The following is no registration authority for names an example of extension
properties and this property parameters. with a pointer to the
directory information associated with the organizer:

ORGANIZER;CN=JohnSmith;DIR="ldap://host.com:6666/o=3DDC%20Associ
ates,c=3DUS??(cn=3DJohn%20Smith)":MAILTO:jsmith@host1.com

The data type for following is an example of this property used by another calendar
user who is TEXT. Optionally, the data type MAY be any acting on behalf of the other valid data
types.

5. Recommended Practices

These recommended practices should organizer, with responses
intended to be followed in order sent back to assure
consistent handling of the following cases for an iCalendar object.

1.
A organizer, not the other calendar entry with a "DTSTART" property but no "DTEND"
user:

ORGANIZER;SENT-BY="MAILTO:jane_doe@host.com":
MAILTO:jsmith@host1.com

4.8.4.4 Recurrence ID

Property Name: RECURRENCE-ID

Purpose: This property
- The event does not take up any time. It is intended to represent
an event that is associated with a given calendar date and time of
day, such as an anniversary. Since the event does not take up any

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time, it MUST NOT be used to record busy time no matter what the
value for the "TRANSP" property.

2.
When in conjunction with the "DTSTART" "UID" and "DTEND", for
"SEQUENCE" property to identify a specific instance of a recurring
"VEVENT", "VTODO" or "VJOURNAL" and
"VFREEBUSY" calendar components, and component. The property
value is the effective value of the "DTSTART" and "DUE", for
"VTODO" calendar components, have property of the same
recurrence instance.

Value Type: The default value data type (e.g.,
DATE-TIME), they should specify values in the same for this property is DATE-TIME.
The time format
(e.g., local time with UTC offset).

3.
A combination MAY BE any of "RRULE" and "RDATE" properties that produces more
than one instance the valid forms defined for a given date/time - Only one recurrence can
occur on a given date/time interval. Just one instance DATE-TIME
value type. See DATE-TIME value type definition for specific
interpretations of the
date/time is recorded.

4.
A particular various forms. The value type MAY be reset to
DATE.

Conformance: This property MAY be specified in an iCalendar object method that specifies "ATTENDEE"
properties with the "MEMBER" property parameter, for which the
recipient has multiple memberships - Recipient should reply
containing a recurring calendar component.

Description: The full range of calendar components specified by a
recurrence set is referenced by referring to
only just the first "MEMBER" "UID" property parameter
value that it can
match.

6. Registration of Content Type Elements

This section provide corresponding to the process for registration of MIME Calendaring
and Scheduling Content Type iCalendar object methods and new or
modified properties.

6.1 Registration of New and Modified iCalendar object Methods

New MIME Calendaring and Scheduling Content Type iCalendar object
methods are registered by calendar component. The "RECURRENCE-ID"
property allows the publication of an IETF Request for
Comment (RFC). Changes reference to an iCalendar object method are registered
by the publication of a revision of the RFC defining the method.

6.2 Registration of New Properties

This section defines procedures by which new properties or enumerated
property values for the MIME Calendaring and Scheduling Content Type
can be registered with the IANA. Note that non-IANA properties MAY be
used by bilateral agreement, provided individual instance within the associated properties names
follow
recurrence set.

If the "X-" convention.

The procedures defined here are designed to allow public comment and
review value of new properties, while posing only a small impediment to the
definition of new properties.

Registration of a new "DTSTART" property is accomplished by a DATE type value, then the following
steps.

6.2.1 Define
value MUST be the property

A property is defined by completing calendar date for the following template.

To: ietf-calendar@imc.org recurrence instance.

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Subject: Registration of text/calendar MIME property XXX

Property name:

Property purpose:

Property data type(s):

Property encoding:

Property special notes (optional):

Intended usage: (one of COMMON, LIMITED USE or OBSOLETE) March 6, 1998

The meaning of each field in the template date/time value is as follows.

Property name: The name of set to the property, as it will appear in time when the
body of an text/calendar MIME Content-Type "property: value" line original recurrence
instance would occur - - meaning that if the intent is to change a
Friday meeting to Thursday, the left of date/time is still set to the colon ":".

Property purpose:
original Friday meeting.

The purpose of "RECURRENCE-ID" property is used in conjunction with the "UID"
and "SEQUENCE" property (e.g., to indicate identify a
delegate for the event particular instance of a
recurring event, to-do or to-do, etc.). Give journal. For a short but clear
description.

Property data type(s): Any given pair of the valid data types for the "UID" and
"SEQUENCE" property values, the "RECURRENCE-ID" value needs to be specified. The default data type also needs to be
specified. If for a new data type is specified, it needs to be declared
in this section.

Property special notes: Any special notes about the property, how it
recurrence instance is to be used, etc.

6.2.2 Post fixed. When the Property definition

The property description MUST be posted to of the new property
discussion list, ietf-calendar@imc.org.

6.2.3 Allow recurrence
set for a comment period

Discussion on calendar component changes, and hence the new "SEQUENCE"
property MUST be allowed to take place on value changes, the
list "RECURRENCE-ID" for a minimum of two weeks. Consensus MUST be reached on the
property before proceeding given recurrence
instance might also change.The "RANGE" parameter is used to specify
the next step.

6.2.4 Submit effective range of recurrence instances from the instance
specified by the "RECURRENCE-ID" property value. The default value
for approval

Once the two-week comment period has elapsed, and the proposer range parameter is
convinced consensus has been reached on the property, the
registration application should single recurrence instance only. The
value can also be submitted "THISANDPRIOR" to indicate a range defined by the Method Reviewer
for approval. The Method Reviewer is appointed to the Application
Area Directors
given recurrence instance and MAY either accept all prior instances or reject the property
registration. An accepted registration should value can be passed on
"THISANDFUTURE" to indicate a range defined by the
Method Reviewer to given recurrence
instance and all subsequent instances.

Only the IANA for inclusion in "VALUE" property parameter and the official IANA method
registry. The registration property-specific "RANGE"
parameter MAY be rejected for any of specified on this property.

Format Definition: The property is defined by the following
reasons. 1) Insufficient comment period; 2) Consensus not reached; 3) notation:

recurid = "RECURRENCE-ID" *(";" [WSP] parameter)
[";" [WSP] rangeparm] ":" [WSP] [date-time / date]
;Value must match value type.

recurid = "RECURRENCE-ID" [ridparam] [rangeparm] ":" [WSP]
ridval CRLF

ridparam = ";" [WSP] "VALUE" "=" ("DATE-TIME" / "DATE" /
/ "PERIOD")

rangeparm = ";" [WSP] "RANGE" "=" ("THISANDPRIOR"
/ "THISANDFUTURE")

ridval = date-time / date / period
;Value MUST match value type

Example: The following are examples of this property:

RECURRENCE-ID;VALUE=DATE:19960401

RECURRENCE-ID;RANGE=THISANDFUTURE:19960120T120000Z

4.8.4.5 Related To

Property Name: RELATED-TO

Purpose: The property is used to represent a relationship or
reference between one calendar component and another.

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Technical deficiencies raised on the list or elsewhere have not been
addressed. March 6, 1998

Value Type: TEXT

Conformance: The Method Reviewer's decision to reject a property MAY only be
appealed by the proposer to specified once in the IESG, or "VEVENT",
"VTODO" and "VJOURNAL" calendar components.

Description: The property value consists of the objections raised can persistent, globally
unique identifier of another calendar component. This value would be
addressed
represented in a calendar component by the proposer and "UID" property.

By default, the property resubmitted.

6.3 Property Change Control

Existing properties MAY be changed using the same process by which
they were registered.

1.
Define the change

2.
Post the change

3.
Allow a comment period

4.
Submit the property for approval

Note value points to another calendar component
that the original author or any other interested party MAY
propose has a change PARENT relationship to an existing property, but that such changes
should only be proposed when there are serious omissions or errors in the published memo. referencing object. The Method Reviewer MAY object to a change if it
is not backwards compatible, but
"RELTYPE" property parameter is not required used to do so.

Property definitions can never be deleted from either explicitly state the IANA registry, but
properties which are no longer believed
default PARENT relationship type to be useful can be declared
OBSOLETE by a change the referenced calendar component
or to their "intended use" field.

7. File extension override the default PARENT relationship type and specify
either a CHILD or SIBLING relationship. The file extension of "vcs" PARENT relationship
indicates that the calendar component is to be used to designate a file
containing calendaring and scheduling information consistent with
this MIME content type.

8. Macintosh File Type Code subordinate of the
referenced calendar component. The file type code CHILD relationship indicates that
the calendar component is a superior of "vcal" the referenced calendar
component. The SIBLING relationship indicates that the calendar
component is a peer of the referenced calendar component.

Changes to be used in Apple MacIntosh
operating system environments to designate a file containing
calendaring and scheduling information consistent with calendar component referenced by this MIME
media type.

9. References

The following document are referred property MAY have
an implied impact to within the related calendar component. For example, if
a group event changes its start or end date or time, then the
related, dependent events will need to have their start and end dates
changed in a corresponding way. Similarly, if a PARENT calendar
component is canceled or deleted, then there is an implied impact to
the related CHILD calendar components. This property is intended only
to provide information on the relationship of calendar components. It
is up to the target calendar system to maintain any property
implications of this memo.

[ICMS] "Internet Calendaring Model Specification", Internet-Draft,
July 1997, ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-mod-
03.txt.

[IMIP] "iCalendar Message-based Interoperability Protocol (IMIP)",
Internet Draft, October 1997, http://www.imc.org/draft-ietf-calsch-
imip-03.txt. relationship.

Only the property specific "RELTYPE" parameter MAY be specified on
this property.

Format Definition: The property is defined by the following notation:

related = "RELATED-TO" [";" [WSP] relparam) ":" [WSP] text CRLF

relparam = "RELTYPE" "="
"PARENT" ; Parent relationship. Default.
/ "CHILD" ; Child relationship.
/ "SIBLING" ; Sibling relationship.

The following is an example of this property:

RELATED-TO:<jsmith.part7.19960817T083000.xyzMail@host3.com>

RELATED-TO:<19960401-080045-4000F192713-0052@host1.com>

4.8.4.6 Uniform Resource Locator

Property Name: URL

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[ISO 8601] ISO 8601, "Data elements and interchange formats_
Information interchange--Representation of dates March 6, 1998

Purpose: This property defines a Uniform Resource Locator (URL)
associated with the iCalendar object.

Value Type: URI

Conformance: This property MAY be specified once in the "VEVENT",
"VTODO", "VJOURNAL" and times",
International Organization for Standardization, June, 1988. "VFREEBUSY" calendar components.

Description: This
standard is also addressed by property may be used in a calendar component to
convey a location where a more dynamic rendition of the Internet Draft document
ftp://ds.internic.net/internet-drafts/draft-newman-datetime-00.txt.

[ISO 9070] ISO/IEC 9070, "Information Technology_SGML Support
Facilities--Registration Procedures for Public Text Owner
Identifiers", Second Edition, International Organization for
Standardization, April, 1991.

[ITIP] "iCalendar Transport-Independent Interoperability Protocol
(iTIP) : Scheduling Events, Busy Time, To-dos and Journal Entries ",
Internet-Draft, October 1997, http://www.imc.org/draft-ietf-calsch-
itip-02.txt.

[MIME DIR] Howes, T., Smith, M., "A MIME Content-Type for Directory
Information", Internet-draft-ietf-asid-mime-direct-07.txt, November,
1997.

[RFC 822] Crocker, D., "Standard for calendar
information associated with the Format calendar component can be found. This
memo does not attempt to standardize the form of ARPA Internet Text
Messages", STD 11, RFC 822, August 1982.

[RFC 1738] Berners-Lee, T., Masinter, L., McCahill, M., "Uniform
Resource Locators (URL)", RFC 1738, December 1994.

[RFC 1766] Alvestrand, H., "Tags for the Identification URI, nor the
format of
Languages", March 1995.

[RFC 1872] Levinson, E., "The MIME Multipart/Related Content-type,"
RFC 1872, December 1995.

[RFC 1983] "Internet Users' Glossary", RFC 1983, August 1996.

[RFC 2045] Freed, N., Borenstein, N., " Multipurpose Internet Mail
Extensions (MIME) - Part One: the resource pointed to by the property value. If the

No property parameter MAY be specified on this property.

Format Definition: The property is defined by the following notation:

url = "URL" ":" [WSP] uri CRLF

Example: The following is an example of Internet Message Bodies", RFC
2045, November 1996.

[RFC 2046] Freed, N., Borenstein, N., " Multipurpose Internet Mail
Extensions (MIME) - Part Two: Media Types", RFC 2046, November 1996.

[RFC 2047] Moore, K., "Multipurpose Internet Mail Extensions (MIME) -
Part Three: Message Header Extensions this property:

URL:http://abc.com/pub/calendars/jsmith/mytime.or3

4.8.4.7 Unique Identifier

Property Name: UID

Purpose: This property defines the persistent, globally unique
identifier for Non-ASCII Text", RFC 2047,
November 1996. the calendar component.

Value Type: TEXT

Conformance: The property MUST be specified in the "VEVENT", "VTODO",
"VJOURNAL" and "VFREEBUSY" calendar components.

Description: The UID itself MUST be a globally unique identifier. The
generator of the identifier MUST guarantee that the identifier is
unique. There are several algorithms that can be used to accomplish
this. The identifier is RECOMMENDED to be the identical syntax to the
[RFC 2048] Freed, N., J. Klensin, J. Postel, "Multipurpose 822] addr-spec. A good method to assure uniqueness is to put the
domain name or a domain literal IP address of the host on which the
identifier was created on the right hand side of the "@", and on the
left hand side, put a combination of the current calendar date and
time of day (i.e., formatted in as a DATE-TIME value) along with some
other currently unique (perhaps sequential) identifier available on
the system (for example, a process id number). Using a date/time
value on the left hand side and a domain name or domain literal on
the right hand side makes it possible to guarantee uniqueness since
no two hosts should be using the same domain name or IP address at
the same time. Though other algorithms will work, it is RECOMMENDED
that the right hand side contain some domain identifier (either of
the host itself or otherwise) such that the generator of the message

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identifier can guarantee the uniqueness of the left hand side within
the scope of that domain.

This is the method for correlating scheduling messages with the
referenced "VEVENT", "VTODO", or "VJOURNAL" calendar component.

The full range of calendar components specified by a recurrence set
is referenced by referring to just the "UID" property value
corresponding to the calendar component. The "RECURRENCE-ID" property
allows the reference to an individual instance within the recurrence
set.

This property is an important method for group scheduling
applications to match requests with later replies, modifications or
deletion requests. Calendaring and scheduling applications MUST
generate this property in "VEVENT", "VTODO" and "VJOURNAL" calendar
components to assure interoperability with other group scheduling
applications. This identifier is created by the calendar system that
generates an iCalendar object.

Implementations MUST be able to receive and persist values of at
least 255 characters for this property.

No property parameter MAY be specified on this property.

Format Definition: The property is defined by the following notation:

uid = "UID" ":" [WSP] text CRLF

Example: The following is an example of this property:

UID:19960401T080045Z-4000F192713-0052@host1.com

4.8.5 Recurrence Component Properties

The following properties specify recurrence information in calendar
components.

4.8.5.1 Exception Date/Times

Property Name: EXDATE

Purpose: This property defines the list of date/time exceptions for a
recurring calendar component.

Value Type: The default value type for this property is DATE-TIME.
The value type MAY be reset to DATE.

Conformance: This property MAY be specified in an iCalendar object
that includes a recurring calendar component.

Description: The exception dates, if specified, is used in computing
the recurrence set. The recurrence set is the complete set of
recurrence instances for a calendar component. The recurrence set is

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generated by considering the initial "DTSTART" property along with
the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
within the iCalendar object. The "DTSTART" property defines the first
instance in the recurrence set. Multiple instances of the "RRULE" and
"EXRULE" properties MAY also be specified to define more
sophisticated recurrence sets. The final recurrence set is generated
by gathering all of the start date-times generated by any of the
specified "RRULE" and "RDATE" properties, and excluding any start
date and times which fall within the union of start date and times
generated by any specified "EXRULE" and "EXDATE" properties. This
implies that start date and times within exclusion related properties
(i.e., "EXDATE" and "EXRULE") take precedence over those specified by
inclusion properties (i.e., "RDATE" and "RRULE"). Where duplicate
instances are generated by the "RRULE" and "RDATE" properties, only
one recurrence is considered. Duplicate instances are ignored.

The "EXDATE" property MAY be used to exclude the value specified in
"DTSTART". However, in such cases the original "DTSTART" date MUST
still be maintained by the calendaring and scheduling system because
the original "DTSTART" value has inherent usage dependencies by other
properties such as the "RECURRENCE-ID".

Only the "VALUE" and "TZID" property parameters MAY be specified on
this property. The "TZID" property parameter MAY only be specified
when the value type is DATE-TIME.

Format Definition: The property is defined by the following notation:

exdate = "EXDATE" [exdtparam] ":" [WSP] exdtval CRLF

exdtparam = [";" [WSP] "VALUE" "=" "DATE-TIME"]
[";" [WSP] "TZID" "=" paramtext]

exdtparam =/ ";" [WSP] "VALUE" "=" "DATE"

exdtval = date-time / date
;Value MUST match value type

Example: The following is an example of this property:

EXDATE:19960402T010000Z,19960403T010000Z,19960404T010000Z

4.8.5.2 Exception Rule

Property Name: EXRULE

Purpose: This property defines a rule or repeating pattern for an
exception to a recurrence set.

Value Type: RECUR

Conformance: This property MAY only be specified in the "VEVENT",
"VTODO" or "VJOURNAL" calendar components.

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Description: The exception rule, if specified, is used in computing
the recurrence set. The recurrence set is the complete set of
recurrence instances for a calendar component. The recurrence set is
generated by considering the initial "DTSTART" property along with
the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
within the iCalendar object. The "DTSTART" defines the first instance
in the recurrence set. Multiple instances of the "RRULE" and "EXRULE"
properties MAY also be specified to define more sophisticated
recurrence sets. The final recurrence set is generated by gathering
all of the start date-times generated by any of the specified "RRULE"
and "RDATE" properties, and excluding any start date and times which
fall within the union of start date and times generated by any
specified "EXRULE" and "EXDATE" properties. This implies that start
date and times within exclusion related properties (i.e., "EXDATE"
and "EXRULE") take precedence over those specified by inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
generated by the "RRULE" and "RDATE" properties, only one recurrence
is considered. Duplicate instances are ignored.

The "EXRULE" property MAY be used to exclude the value specified in
"DTSTART". However, in such cases the original "DTSTART" date MUST
still be maintained by the calendaring and scheduling system because
the original "DTSTART" value has inherent usage dependencies by other
properties such as the "RECURRENCE-ID".

No property parameters MAY be specified on this property.

Format Definition: The property is defined by the following notation:

exrule = "EXRULE" ":" [WSP] recur CRLF

Example: The following are examples of this property. Except every
other week, on Tuesday and Thursday for 4 occurrences:

EXRULE:FREQ=WEEKLY;COUNT=4;INTERVAL=2;BYDAY=TU,TH

Except daily for 10 occurrences:

EXRULE:FREQ=DAILY;COUNT=10

Except yearly in June and July for 8 occurrences:

EXRULE:FREQ=YEARLY;COUNT=8;BYMONTH=6,7

The data type for this property is RECUR.

4.8.5.3 Recurrence Date/Times

Property Name: RDATE

Purpose: This property defines the list of date/times for a
recurrence set.

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Value Type: The default value type for this property is DATE-TIME.
The value type MAY be reset to DATE or PERIOD.

Conformance: The property MAY only appear within the "VEVENT",
"VTODO", "VJOURNAL" or "VTIMEZONE" calendar components.

Description: This property MAY appear along with the "RRULE" property
to define an aggregate set of repeating occurrences. When they both
appear in an iCalendar object, the recurring events are defined by
the union of occurrences defined by both the "RDATE" and "RRULE".

The recurrence dates, if specified, is used in computing the
recurrence set. The recurrence set is the complete set of recurrence
instances for a calendar component. The recurrence set is generated
by considering the initial "DTSTART" property along with the "RRULE",
"RDATE", "EXDATE" and "EXRULE" properties contained within the
iCalendar object. The "DTSTART" property defines the first instance
in the recurrence set. Multiple instances of the "RRULE" and "EXRULE"
properties MAY also be specified to define more sophisticated
recurrence sets. The final recurrence set is generated by gathering
all of the start date-times generated by any of the specified "RRULE"
and "RDATE" properties, and excluding any start date and times which
fall within the union of start date and times generated by any
specified "EXRULE" and "EXDATE" properties. This implies that start
date and times within exclusion related properties (i.e., "EXDATE"
and "EXRULE") take precedence over those specified by inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
generated by the "RRULE" and "RDATE" properties, only one recurrence
is considered. Duplicate instances are ignored.

Only the "VALUE" and "TZID" property parameters MAY be specified on
this property. The "TZID" property parameter MAY only be specified
when the value type is DATE-TIME.

Format Definition: The property is defined by the following notation:

rdate = "RDATE" [rdtparam] ":" [WSP] rdtval
*("," [WSP] rdtval) CRLF

rdtparam = [";" [WSP] "VALUE" "=" "DATE-TIME"]
[";" [WSP] "TZID" "=" paramtext]

rdtparam =/ ";" [WSP] "VALUE" "=" "DATE"

rdtparam =/ ";" [WSP] "VALUE" "=" "PERIOD"

rdtval = date-time / date / period
;Value MUST match value type

Example: The following are examples of this property:

RDATE:19970714T123000Z

RDATE;TZID=EST:19970714T083000

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RDATE;VALUE=PERIOD:19960403T020000Z/19960403T040000Z,
19960404T010000Z/PT3H

RDATE;VALUE=DATE:19970101,19970120,19970217,19970421
19970526,19970704,19970901,19971014,19971128,19971129,19971225

4.8.5.4 Recurrence Rule

Property Name: RRULE

Purpose: This property defines a rule or repeating pattern for a
recurring events, to-dos, or time zone definitions.

Value Type: RECUR

Conformance: This property MAY be specified one or more times in
recurring "VEVENT", "VTODO" and "VJOURNAL" calendar components. It
MAY also be specified once in the "VTIMEZONE" calendar component.

Description: The recurring rule, if specified, is used in computing
the recurrence set. The recurrence set is the complete set of
recurrence instances for a calendar component. The recurrence set is
generated by considering the initial "DTSTART" property along with
the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
within the iCalendar object. The "DTSTART" property defines the first
instance in the recurrence set. Multiple instances of the "RRULE" and
"EXRULE" properties MAY also be specified to define more
sophisticated recurrence sets. The final recurrence set is generated
by gathering all of the start date-times generated by any of the
specified "RRULE" and "RDATE" properties, and excluding any start
date and times which fall within the union of start date and times
generated by any specified "EXRULE" and "EXDATE" properties. This
implies that start date and times within exclusion related properties
(i.e., "EXDATE" and "EXRULE") take precedence over those specified by
inclusion properties (i.e., "RDATE" and "RRULE"). Where duplicate
instances are generated by the "RRULE" and "RDATE" properties, only
one recurrence is considered. Duplicate instances are ignored.

The "DTSTART" and "DTEND" property pair or "DTSTART" and "DURATION"
property pair, specified within the iCalendar object defines the
first instance of the recurrence. When used with a recurrence rule,
the "DTSTART" and "DTEND" properties MUST be specified in local time
and the appropriate set of "VTIMEZONE" calendar components MUST be
included. For detail on the usage of the "VTIMEZONE" calendar
component, see the "VTIMEZONE" calendar component definition.

Any duration associated with the iCalendar object applies to all
members of the generated recurrence. Any modified duration for
specific recurrences would have to be explicitly specified using the
"RDATE" property.

No property parameters MAY be specified on this property.

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Format Definition: This property is defined by the following
notation:

rrule = "RRULE" ":" [WSP] recur CRLF

Example: All examples assume the Eastern United States time zone.

Daily for 10 occurrences:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=DAILY;COUNT=10

==> (1997 9AM EDT)September 2-11

Daily until 12/24/97:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z

==> (1997 9AM EDT)September 2-30;October 1-25
(1997 9AM EST)October 26-31;November 1-30;December 1-23

Every other day - forever:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=DAILY;INTERVAL=2
==> (1997 9AM EDT)September2,4,6,8...24,26,28,30;
October 2,4,6...20,22,24
(1997 9AM EST)October 26,28,30;November 1,3,5,7...25,27,29;
Dec 1,3,...

Every 10 days, 5 occurrences:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5

==> (1997 9AM EDT)September 2,12,22;October 2,12

Everyday in January, for 3 years:

DTSTART;TZID=America-New York:19980101T090000
RRULE;TZID=America-New York:FREQ=YEARLY;UNTIL:20000131T090000;
BYMONTH=1;BYDAY=SU,MO,TU,WE,TH,FR,SA
or
RRULE;TZID=America-New York:FREQ=DAILY;UNTIL:20000131T090000;
BYMONTH=1

==> (1998 9AM EDT)January 1-31
(1999 9AM EDT)January 1-31
(2000 9AM EDT)January 1-31

Weekly for 10 occurrences

DTSTART;TZID=America-New York:19970902T090000

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RRULE:FREQ=WEEKLY;COUNT=10

==> (1997 9AM EDT)September 2,9,16,23,30;October 7,14,21
(1997 9AM EST)October 28;November 4

Weekly until 12/24/94

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=WEEKLY;UNTIL=19971224T000000Z

==> (1997 9AM EDT)September 2,9,16,23,30;October 7,14,21
(1997 9AM EST)October 28;November 4,11,18,25;
December 2,9,16,23

Every other week - forever:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;WKST=SU

==> (1997 9AM EDT)September 2,16,30;October 14
(1997 9AM EST)October 28;November 11,25;December 9,23
(1998 9AM EST)January 6,20;February
...

Weekly on Tuesday and Thursday for 5 weeks:

DTSTART;TZID=America-New York:19970902T090000
RRULE;TZID=America-New York:FREQ=WEEKLY;UNTIL=19971007T000000;
WKST=SU;BYDAY=TU,TH
or
RRULE:FREQ=WEEKLY;COUNT=10;WKST=SU;BYDAY=TU,TH

==> (1997 9AM EDT)September 2,4,9,11,16,18,23,25,30;October 2

Every other week on Monday, Wednesday and Friday until 12/24/97, but
starting on Tuesday, 9/2/97:

DTSTART;TZID=America-New York:19970902T090000
RRULE;TZID=America-New York:FREQ=WEEKLY;INTERVAL=2;UNTIL=
19971224T000000;WKST=SU;BYDAY=MO,WE,FR
==> (1997 9AM EDT)September 2,3,5,15,17,19,29;October 1,3,13,15,17
(1997 9AM EST)October 27,29,31;November 10,12,14,24,26,28;
December 8,10,12,22

Every other week on Tuesday and Thursday, for 8 occurrences:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH

==> (1997 9AM EDT)September 2,4,16,18,30;October 2,14,16

Monthly on the 1st Friday for ten occurrences:

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DTSTART;TZID=America-New York:19970905T090000
RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR

==> (1997 9AM EDT)September 5;October 3
(1997 9AM EST)November 7;Dec 5
(1998 9AM EST)January 2;February 6;March 6;April 3
(1998 9AM EDT)MAY 1;June 5

Monthly on the 1st Friday until 12/24/94:

DTSTART;TZID=America-New York:19970905T090000
RRULE:FREQ=MONTHLY;UNTIL=19971224T000000Z;BYDAY=1FR

==> (1997 9AM EDT)September 5;October 3
(1997 9AM EST)November 7;December 5

Every other month on the 1st and last Sunday of the month for 10
occurrences:

DTSTART;TZID=America-New York:19970907T090000
RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;BYDAY=1SU,-1SU

==> (1997 9AM EDT)September 7,28
(1997 9AM EST)November 2,30
(1998 9AM EST)January 4,25;March 1,29
(1998 9AM EDT)MAY 3,31

Monthly on the second to last Monday of the month for 6 months:

DTSTART;TZID=America-New York:19970922T090000
RRULE:FREQ=MONTHLY;COUNT=6;BYDAY=-2MO

==> (1997 9AM EDT)September 22;October 20
(1997 9AM EST)November 17;December 22
(1998 9AM EST)January 19;February 16

Monthly on the third to the last day of the month, forever:

DTSTART;TZID=America-New York:19970928T090000
RRULE:FREQ=MONTHLY;BYMONTHDAY=-3

==> (1997 9AM EDT)September 28
(1997 9AM EST)October 29;November 28;December 29
(1998 9AM EST)January 29;February 26
...

Monthly on the 2nd and 15th of the month for 10 occurrences:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=2,15

==> (1997 9AM EDT)September 2,15;October 2,15
(1997 9AM EST)November 2,15;December 2,15
(1998 9AM EST)January 2,15

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Monthly on the first and last day of the month for 10 occurrences:

DTSTART;TZID=America-New York:19970930T090000
RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=1,-1

==> (1997 9AM EDT)September 30;October 1
(1997 9AM EST)October 31;November 1,30;December 1,31
(1998 9AM EST)January 1,31;February 1

Every 18 months on the 10th thru 15th of the month for 10
occurrences:

DTSTART;TZID=America-New York:19970910T090000
RRULE:FREQ=MONTHLY;INTERVAL=18;COUNT=10;BYMONTHDAY=10,11,12,13,14,
15

==> (1997 9AM EDT)September 10,11,12,13,14,15
(1999 9AM EST)March 10,11,12,13

Every Tuesday, every other month:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=MONTHLY;INTERVAL=2;BYDAY=TU

==> (1997 9AM EDT)September 2,9,16,23,30
(1997 9AM EST)November 4,11,18,25
(1998 9AM EST)January 6,13,20,27;March 3,10,17,24,31
...

Yearly in June and July for 10 occurrences:

DTSTART;TZID=America-New York:19970610T090000
RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7

==> (1997 9AM EDT)June 10;July 10
(1998 9AM EDT)June 10;July 10
(1999 9AM EDT)June 10;July 10
(2000 9AM EDT)June 10;July 10
(2001 9AM EDT)June 10;July 10
Note: Since none of the BYDAY, BYMONTHDAY or BYYEARDAY components
are specified, the day is gotten from DTSTART

Every other year on January, February, and March for 10 occurrences:

DTSTART;TZID=America-New York:19970310T090000
RRULE:FREQ=YEARLY;INTERVAL=2;COUNT=10;BYMONTH=1,2,3

==> (1997 9AM EST)March 10
(1999 9AM EST)January 10;February 10;March 10
(2001 9AM EST)January 10;February 10;March 10
(2003 9AM EST)January 10;February 10;March 10

Every 3rd year on the 1st, 100th and 200th day for 10 occurrences:

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DTSTART;TZID=America-New York:19970101T090000
RRULE:FREQ=YEARLY;INTERVAL=3;COUNT=10;BYYEARDAY=1,100,200

==> (1997 9AM EST)January 1
(1997 9AM EDT)April 10;July 19
(2000 9AM EST)January 1
(2000 9AM EDT)April 9;July 18
(2003 9AM EST)January 1
(2003 9AM EDT)April 10;July 19
(2006 9AM EST)January 1

Every 20th Monday of the year, forever:

DTSTART;TZID=America-New York:19970519T090000
RRULE:FREQ=YEARLY;BYDAY=20MO

==> (1997 9AM EDT)MAY 19
(1998 9AM EDT)MAY 18
(1999 9AM EDT)MAY 17
...

Monday of Week No. 20, forever:

DTSTART;TZID=America-New York:19970512T090000
RRULE:FREQ=YEARLY;BYWEEKNO=20;BYDAY=MO

==> (1997 9AM EDT)MAY 12
(1998 9AM EDT)MAY 11
(1999 9AM EDT)MAY 17
...

Every Thursday in March, forever:

DTSTART;TZID=America-New York:19970313T090000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=TH

==> (1997 9AM EST)March 13,20,27
(1998 9AM EST)March 5,12,19,26
(1999 9AM EST)March 4,11,18,25
...

Every Thursday, but only during summer months, forever:

DTSTART;TZID=America-New York:19970605T090000
RRULE:FREQ=YEARLY;BYDAY=TH;BYMONTH=6,7,8

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Every Friday the 13th, forever:

DTSTART;TZID=America-New York:19970902T090000
EXDATE;TZID=America-New York:19970902T090000
RRULE:FREQ=MONTHLY;BYDAY=FR;BYMONTHDAY=13

==> (1998 9AM EST)February 13;March 13;November 13
(1999 9AM EDT)August 13
(2000 9AM EDT)October 13
...

The first Saturday that follows the first Sunday of the month,
forever:

DTSTART;TZID=America-New York:19970913T090000
RRULE:FREQ=MONTHLY;BYDAY=SA;BYMONTHDAY=7,8,9,10,11,12,13

==> (1997 9AM EDT)September 13;October 11
(1997 9AM EST)November 8;December 13
(1998 9AM EST)January 10;February 7;March 7
(1998 9AM EDT)April 11;MAY 9;June 13...
...

Every four years, the first Tuesday after a Monday in November,
forever (U.S. Presidential Election day):

DTSTART;TZID=America-New York:19961105T090000
RRULE:FREQ=YEARLY;INTERVAL=4;BYMONTH=11;BYDAY=TU;BYMONTHDAY=2,3,4,
5,6,7,8

==> (1996 9AM EST)November 5
(2000 9AM EST)November 7
(2004 9AM EST)November 2
...

The 3rd instance into the month of one of Tuesday, Wednesday or
Thursday, for the next 3 months:

DTSTART;TZID=America-New York:19970904T090000
RRULE:FREQ=MONTHLY;COUNT=3;BYDAY=TU,WE,TH;BYSETPOS=3

==> (1997 9AM EDT)September 4;October 7
(1997 9AM EST)November 6

The 2nd to last weekday of the month:

DTSTART;TZID=America-New York:19970929T090000
RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-2

==> (1997 9AM EDT)September 29
(1997 9AM EST)October 30;November 27;December 30
(1998 9AM EST)January 29;February 26;March 30
...

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Every 3 hours from 9AM to 5PM on a specific day:

DTSTART;TZID=America-New York:19970902T090000
RRULE;TZID=America-New York:FREQ=HOURLY;INTERVAL=3;
UNTIL=19970902T170000

==> (September 2, 1997 EDT)09:00,12:00,15:00

Every 15 minutes for 6 occurrences:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=MINUTELY;INTERVAL=15;COUNT=6

==> (September 2, 1997 EDT)09:00,09:15,09:30,09:45,10:00,10:15

Every hour and a half for 4 occurrences:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=MINUTELY;INTERVAL=90;COUNT=4

==> (September 2, 1997 EDT)09:00,10:30;12:00;13:30

Every 20 minutes from 9AM to 4:40PM every day:

DTSTART;TZID=America-New York:19970902T090000
RRULE:FREQ=DAILY;BYHOUR=9,10,11,12,13,14,15,16;BYMINUTE=0,20,40
or
RRULE:FREQ=MINUTELY;INTERVAL=20;BYHOUR=9,10,11,12,13,14,15,16

==> (September 2, 1997 EDT)9:00,9:20,9:40,10:00,10:20,
... 16:00,16:20,16:40
(September 3 1997 EDT)9:00,9:20,9:40,10:00,10:20,
...16:00,16:20,16:40
...

An example where the days generated makes a difference because of
WKST:

DTSTART;TZID=America-New York:19970805T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=MO

==> (1997 EDT)Aug 5,10,19,24

changing only WKST from MO to SU, yields different results...

DTSTART;TZID=America-New York:19970805T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=SU
==> (1997 EDT)August 5,17,19,31

4.8.6 Alarm Component Properties

The following properties specify alarm information in calendar
components.

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4.8.6.1 Alarm Type

Property Name: ALARM-TYPE

Purpose: This property defines the type of alarm.

Value Type: TEXT

Conformance: This property MUST be specified once within a "VALARM"
calendar component.

Description: Each "VALARM" calendar component is of a particular
type. This property specifies the alarm type. Only the "LANGUAGE"
property parameter MAY be specified on this property.

Format Definition: The property is defined by the following notation:

alarm-type = "ALARM-TYPE" [almtypparam] ":" [WSP] almtypvalue CRLF

almtypparam = ";" [WSP] languageparm

almtypvalue = "AUDIO" / "DISPLAY" / "EMAIL" / "PROCEDURE"
/ iana-token / x-name

Example: The following are examples of this property in a "VALARM"
calendar component:

CATEGORIES:AUDIO,DISPLAY

CATEGORIES:PROCEDURE

4.8.6.2 Repeat Count

Property Name: REPEAT

Purpose: This property defines the number of time the alarm should be
repeated, after the initial trigger.

Value Type: INTEGER

Conformance: This property MAY only be specified in a "VALARM"
calendar component.

Description: If the alarm triggers more than once, then this property
MUST be specified; along with the "DURATION" property.

No property parameter MAY be specified on this property.

Format Definition: The property is defined by the following notation:

repeatcnt = "REPEAT" ":" [WSP] integer CRLF
;Default is "0", zero.

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Example: The following is an example of this property for an alarm
that repeats 4 additional times with a 5 minute delay after the
initial triggering of the alarm.:

REPEAT:4
DURATION:PT5M

4.8.6.3 Trigger

Property Name: TRIGGER

Purpose: This property specifies when an alarm will trigger.

Value Type: The default value type is DURATION. The value type MAY BE
reset to a DATE-TIME value type.

Conformance: This property MUST be specified within the "VALARM"
calendar component.

Description: Within the "VALARM" calendar component, this property
defines when the alarm will trigger. The default value type is
DURATION, specifying a relative time for the trigger of the alarm.
The default duration is relative to the start of an event or to-do
that the alarm is associated with. The duration can be explicitly set
to trigger from either the end or the start of the associated event
or to-do with the "RELATED" parameter. A value of START will set the
alarm to trigger off the start of the associated event or to-do. A
value of END will set the alarm to trigger off the end of the
associated event or to-do.

Either a positive or negative duration may be specified for the
"TRIGGER" property. An alarm with a positive duration is triggered
before the associated start or end of the event or to-do. An alarm
with a negative duration is triggered after the associated start or
end of the event or to-do.

This parameter is not valid if the value type of the property is
reset to DATE-TIME, in order to specify an absolute trigger for the
alarm. If a value type of DATE-TIME is specified, then the value MUST
be specified in the UTC time format. If an absolute trigger is
specified on an alarm for a recurring event or to-do, then the alarm
will only trigger for the specified absolute date/time, along with
any specified repeating instances.

If the trigger is set relative to START, then the "DTSTART" property
must be present in the associated "VEVENT" or "VTODO" calendar
component. If an alarm is specified for an event with the trigger set
relative to the END, then the "DTEND" property or the "DSTART" and
"DURATION' properties must be present in the associated "VEVENT"
calendar component. If the alarm is specified for a to-do with a
trigger set relative to the END, then either the "DUE" property or
the "DSTART" and "DURATION' properties must be present in the
associated "VTODO" calendar component.

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Alarms specified in an event or to-do that is defined solely in terms
of a DATE value type will be triggered relative to midnight on the
day prior to the specified date. For example, if "DTSTART:19980205,
then the a duration trigger will be relative to 19980204T240000Z.

Only the "VALUE" and "TZID" property parameters and property-specific
"RELATED" parameter MAY be specified on this property. The "TZID"
property parameter MAY only be specified when the value type is DATE-
TIME.

Format Definition: The property is defined by the following notation:

trigger = "TRIGGER" (trigrel / trigabs)

trigrel = ([";" [WSP] "VALUE" "=" "DURATION"]
";" [WSP] "RELATED" "=" ("START" / "END"))
":" [WSP] (["+"] / "-") duration

trigabs = (";" [WSP] "VALUE" "=" "DATE-TIME"
":" [WSP] date-time)

Example: A trigger set 15 minutes relative to the start of the event
or to-do.

TRIGGER:P15M

A trigger set 5 minutes relative to the end of the event or to-do.

TRIGGER;RELATED=END:P5M

A trigger set to an absolute date/time.

TRIGGER;VALUE=DATE-TIME:19980101T050000Z

4.8.7 Change Management Component Properties

The following properties specify change management information in
calendar components.

4.8.7.1 Date/Time Created

Property Name: CREATED

Purpose: This property specifies the date and time that the calendar
information was created in the calendar user agent.

Value Type: DATE-TIME

Conformance: The property MAY be specified in any of the calendar
components. The property MAY only be specified once.

Description: The date and time is a UTC value.

No property parameters MAY be specified on this property.

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Format Definition: The property is defined by the following notation:

created = "CREATED" ":" [WSP] date-time CRLF

Example: The following is an example of this property:

CREATED:19960329T133000Z

4.8.7.2 Date/Time Stamp

Property Name: DTSTAMP

Purpose: The property indicates the date/time that the instance of
the iCalendar object was created.

Value Type: DATE-TIME

Conformance: This property MUST be included in the "VEVENT", "VTODO",
"VJOURNAL" and "VFREEBUSY" calendar components.

Description: The value must be specified in the UTC time format.

This property is also useful to protocols such as [IMIP] that have
inherent latency issues with the delivery of content. This property
will assist in the proper sequencing of messages containing iCalendar
objects.

This property is different than the "CREATED" and "LAST-MODIFIED"
properties. These two properties are used to specify when the
calendar service information was created and last modified. This is
different than when the iCalendar object representation of the
calendar service information was created or last modified.

No property parameters MAY be specified on this property.

Format Definition: The property is defined by the following notation:

dtstamp = "DTSTAMP" ":" [WSP] date-time CRLF

Example:

DTSTAMP:19971210T080000Z

4.8.7.3 Last Modified

Property Name: LAST-MODIFIED

Purpose: The property specifies the date and time that the
information associated with the calendar component was last revised.

Value Type: DATE-TIME

Conformance: This property MAY be specified in the "EVENT", "VTODO",
"VJOURNAL" or "VFREEBUSY" calendar components.

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Description: The property value MUST be specified in the UTC time
format.

No property parameters MAY be specified on this property.

Format Definition: The property is defined by the following notation:

last-mod = "LAST-MODIFIED" ":" [WSP] date-time CRLF

Example: The following is are examples of this property:

LAST-MODIFIED:19960817T133000Z

4.8.7.4 Sequence Number

Property Name: SEQUENCE

Purpose: This property defines the revision sequence of the calendar
component used in a request.

Value Type: INTEGER

Conformance: The property MAY only be specified in a "VEVENT",
"VTODO", "VJOURNAL" or "VFREEBUSY" calendar component.

Description: This property is needed to properly handle the receipt
and processing of a sequence of calendar components that have been
delivered out of order. Such is the case for store-and-forward based
transports. The first request is created with a sequence number of
"0" (ASCII decimal 48). It is incremented each time the ORGANIZER or
OWNER issues a revision to the request. The sequence number MUST be
monotonically incremented when one of the following properties in a
calendar component is changed:

. "DTSTART"
. "DTEND"
. "DUE"
. "RDATE"
. "RRULE"
. "EXDATE"
. "EXRULE"

No property parameter MAY be specified on this property.

Format Definition: The property is defined by the following notation:

seq = "SEQUENCE" ":" [WSP] integer CRLF
;Default is "0".

Example: The following is an example of this property:

SEQUENCE:1

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4.8.8 Miscellaneous Component Properties

The following properties specify information about a number of
miscellaneous features of calendar components.

4.8.8.1 Non-standard Properties

Property Name: Any property name with a "X-" prefix

Purpose: This class of property provides a framework for defining
non-standard properties.

Value Type: TEXT

Conformance: This property MAY be specified in any calendar
component.

Description: The MIME Calendaring and Scheduling Content Type
provides a "standard mechanism for doing non-standard things". This
extension support is provided for implementers to "push the envelope"
on the existing version of the memo. Extension properties are
specified by property and/or property parameter names that have the
prefix text of "X-" (the two character sequence: LATIN CAPITAL LETTER
X character followed by the HYPEN-MINUS character). It is recommended
that vendors concatenate onto this sentinel another short prefix text
to identify the vendor. This will facilitate readability of the
extensions and minimize possible collision of names between different
vendors. User agents that support this content type are expected to
be able to parse the extension properties and property parameters but
MAY ignore them.

At present, there is no registration authority for names of extension
properties and property parameters. The data type for this property
is TEXT. Optionally, the data type MAY be any of the other valid data
types.

Any of the general property parameters MAY be specified on this
property.

Format Definition: The property is defined by the following notation:

extension = "X-" [vendorid] "-" text *(";" [WSP] param) ":"
[WSP] value-list CRLF
; Lines longer than 75 characters should be folded

vendorid = 3*char ;Vendor identification prefix text

Example: The following