Internet DRAFT - draft-hare-xcalendar

draft-hare-xcalendar







Network Working Group                                            T. Hare
Internet-Draft                                                Individual
Expires: November 17, 2005                                  May 16, 2005


            Guideline for use of XML with iCalendar elements
                        draft-hare-xcalendar-03

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
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   This Internet-Draft will expire on November 17, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This memo defines a guideline for using XML to represent calendaring
   information that corresponds to the iCalendar, Internet Calendaring
   and Scheduling Core Object Specification defined by [RFC 2445] and
   the protocols defined by [RFC2446], [RFC2447] and [CAP].  This memo
   applies to all [RFC 2445] extensions and	modifications.

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



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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Using XML For Representing iCalendar . . . . . . . . . . . . .  5
   3.  XML and XSL Dependencies . . . . . . . . . . . . . . . . . . .  6
   4.  Working With Standard and XML iCalendar Representations  . . .  7
   5.  Conversion . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   6.  Mixed Use of Both Representations  . . . . . . . . . . . . . .  9
   7.  Using Data Types . . . . . . . . . . . . . . . . . . . . . . . 10
   8.  Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   9.  Emailing documents with iCalendar XML Representation . . . . . 13
   10.   iCalendar XML Representation and File Systems  . . . . . . . 14
   11.   Example Usage  . . . . . . . . . . . . . . . . . . . . . . . 15
     11.1  Example DTD  . . . . . . . . . . . . . . . . . . . . . . . 15
     11.2  An example XSL transformation  . . . . . . . . . . . . . . 28
     11.3  A well-formed and valid iCalendar XML document . . . . . . 34
     11.4  Including binary content in attachments  . . . . . . . . . 34
     11.5  Including binary content inline  . . . . . . . . . . . . . 35
     11.6  iCalendar XML document with multiple iCalendar objects . . 36
     11.7  Using the iCalendar namespace  . . . . . . . . . . . . . . 37
     11.8  Publish meeting information  . . . . . . . . . . . . . . . 38
     11.9  Publish transparent annual event . . . . . . . . . . . . . 38
     11.10   Meeting invitation . . . . . . . . . . . . . . . . . . . 39
     11.11   Assign a to-do . . . . . . . . . . . . . . . . . . . . . 39
     11.12   Publish busy time  . . . . . . . . . . . . . . . . . . . 40
     11.13   Request busy time  . . . . . . . . . . . . . . . . . . . 41
     11.14   Issue a CAP command  . . . . . . . . . . . . . . . . . . 41
     11.15   A well-formed and valid XML document which can be
             transformed into iCalendar . . . . . . . . . . . . . . . 41
   12.   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . 44
   13.   Security Considerations  . . . . . . . . . . . . . . . . . . 45
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 45
   A.  Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . 46
       Intellectual Property and Copyright Statements . . . . . . . . 48

















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1.  Introduction

   The Extended Markup Language (XML) as defined in [XML] has gained
   widespread attention as a "web friendly" syntax for representing and
   exchanging documents	and data on the Internet.  This interest
   includes requests for and discussion of possible document type
   definitions (DTD) and name-spaces for IETF standard	formats such as
   that defined by [RFC 2445], [RCF 2446], and [RFC 2447].

   This memo defines how XML can be used to represent iCalendar
   objects,and how iCalendar namespaces can be used with other XML
   documents.  An example DTD is provided although use of a DTD is not
   required.

   This memo does not try to enforce any specific one-to-one mapping
   between XML	objects and iCalendar objects, but instead attempts to
   document the method whereby XML developers can provide
   interoperability with iCalendar.

   NOTE: The [RFC 2445] is the definitive reference for the definition
   of iCalendar semantics.  This memo only provides a guideline for
   representing such semantics in XML.  This memo does not introduce any
   new semantics for items already defined by [RFC 2445].  [RFC 2446],
   [RFC 2447], and [CAP] are the references for protocols	for the
   exchange of iCalendar objects.  This memo does not introduce any new
   protocols or functions beyond those in the respective documents.

   An attempt has been made to guide the developer in use of XML to
   represent iCalendar semantics, allowing XML-based applications to
   make use of the iCalendar [RFC2445] and related protocols [RFC2446],
   [RFC2447], and [CAP] semantics and to provide interoperability
   between XML-based applications and iCalendar-compliant	applications.

   The publication of XML version 1.0 was followed by publication of two
   World-wide Web Consortium (W3C) recommendations relevant to this
   memo.  The first was a recommendation on "Namespaces in XML" and the
   other was a recommendation on "Extensible Stylesheet Language" and
   "Extensible Stylesheet Language Transformation" (XSL and XSLT).  An
   XML name-space is a collection of names, identified by a URI.  An XSL
   transformation(XSLT)is a document in the Extensible Stylesheet
   Language (XSL) which provides a method for transforming an XML
   document into some other form.  In anticipation of the use of XML
   namespaces, this memo includes the definition of URIs to be used to
   identify the namespaces for iCalendar [RFC 2445], iTIP [RFC 2446],
   iMIP [RFC 2447] and CAP elements.  XML applications that conform to
   this memo and also use namespaces MAY include other	non-iCalendar
   namespaces.




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   Documents MAY include a Document Type Definition (DTD), an XML
   schema, or may	reference external versions of either.  This memo
   allows documents containing	iCalendar XML objects to be constructed
   with either.  DTDs and Schemas are outside	the scope of this memo.  A
   document containing a DTD or schema MAY include	definitions for
   calendar elements.  Any document conforming to this memo MUST	provide
   an XSL transformation which will render those calendar elements
   into	standard iCalendar/iTIP/iMIP/CAP (as appropriate) elements.











































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2.  Using XML For Representing iCalendar

   XML is a simplified version of the text markup syntax defined by ISO
   8879, Standard Generalized Markup Language (SGML).  XML was published
   as a proposed recommendation [XML] by the World-wide Web Consortium
   (W3C) on February 10, 1998.













































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3.  XML and XSL Dependencies

   This memo specifies the XML representation for the standard iCalendar
   elements defined by [RFC 2445], [RFC 2446], [RFC2447], and [CAP].
   There are no XML dependencies other than the [XML] and the [XMLNS]
   recommendations.

   This memo requires that conforming documents include a reference to
   an [XSL] stylesheet for transforming the document into standard
   iCalendar format.  How the transformation is done is left to the
   implementor.  Providing an XSL transform into iCalendar objects does
   not preclude providing other transforms.







































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4.  Working With Standard and XML iCalendar Representations

   This memo provides a guideline for using alternative, XML
   representations for the standard iCalendar elements defined in [RFC
   2445].  These alternative representations SHOULD provide the same
   semantics as that defined in the standard format.  It is the goal of
   this memo to allow all [RFC 2445] extensions and modifications to be
   translated into and from this XML format.











































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5.  Conversion

   This memo requires any compliant document to be transformable into
   standard iCalendar information.  It is recognized that such
   conversion MAY be asymmetric,	since compliant documents MAY include
   information which is not representable in iCalendar and which would
   be lost during any "round trip" conversions.  This does not preclude
   implementation of "round-trippable" transformations, but they are not
   required.

   To formalize and standardize the interchange of iCalendar information
   through	XML, each conforming document MUST include reference to an
   XSL stylesheet which can transform the document into a standard
   iCalendar [RFC 2445] document of MIME	content-type "text/calendar".





































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6.  Mixed Use of Both Representations

   As previously indicated, conversion between the XML and standard
   representations of iCalendar is a straightforward process using XSL
   transformations.  In addition, mixed use of both representations is
   also possible using MIME objects.

   While MIME multipart content-types can be used to provide a mix of
   both the standard and XML representations, this is NOT required.
   Instead, each document MUST include a reference to an XSL stylesheet
   which can transform the XML representation into standard iCalendar
   (and possibly, iTIP, iMIP, or CAP) syntax.

   With the use of the MIME multipart content-types, compound MIME
   entities containing a mix of the standard and XML representations can
   be specified.  Internet applications conforming to this memo MAY send
   both the standard and XML representation of the iCalendar objects, to
   provide compatibility with Internet applications which cannot process
   the required XSL transformation.
































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7.  Using Data Types

   Strong "data typing" is an integral design principle to the iCalendar
   format.	Strong data typing in iCalendar means that the format type
   for each property	value is well known.  Within [RFC 2445], the data
   type is called the "value type".  The standard format defined by [RFC
   2445] specifies a default value type for each calendar and component
   property.  In addition, many of the property definitions allow for
   the specification of alternate value types.  The required XSL
   transformation in this memo MUST create iCalendar elements with
   proper types.  Consult iCalendar [RFC 2445] for documentation of
   value types.







































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8.  Namespaces

   [XMLNS] defines "Namespaces in XML" to be a collection of names,
   identified by a URI, which are used in XML documents as element types
   and attribute names.  The [XML] specification does not include a
   definition for namespaces, but does set down some guidelines for
   experimental naming of namespaces.

   XML namespaces allow multiple markup vocabulary in a single document.
   Documents	and applications conforming to this memo MAY use multiple
   namespaces with the	iCalendar, iTIP, iMIP, and CAP namespaces.
   Multiple namespaces MUST be used for the different iCalendar and
   protocol elements.  This requirement is intended to provide clarity
   in the document, by discriminating calendar object elements
   from	protocol elements.

   The document at the namespace URI does not contain any defintions but
   serves as a unique identifier to allow specification of different
   namespaces.  Applications complying with this memo MUST use the
   following URIs for namespace elements:

      iCalendar:	http://www.ietf.org/rfc/rfc2445.txt

      iTIP:		http://www.ietf.org/rfc/rfc2446.txt

      iMIP:		http://www.ietf.org/rfc/rfc2447.txt

      CAP:		http://www.ietf.org/internet-drafts/
      draft-ietf-calsch-cap-13.txt

   NOTE: the URI for CAP will be replaced with the RFCxxxx reference
   when CAP is	completed.

   The following is an example of a well-formed but invalid "xdoc"
   document type	that includes elements and attribute lists from the
   iCalendar and iTIP	namespaces.















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                   <?xml version="1.0" encoding="UTF-8"?>
                   <xdoc>
                     <iCal:vcalendar iTIP:method="publish"
                             xmlns:iCal="http://www.ietf.org/rfc/RFC2445.txt"
                             xmlns:iTIP="http://www.ietf.org/rfc/RFC2446.txt">
                     <iCal:vevent>
                     <!--- VEVENT elements go here -->
                     </iCal:vevent>

                     <!-- Remainder of the XML document, each element from the -->
                     <!-- iCalendar namespace with the "iCal:" prefix. -->

                   </xdoc>

   The semantics of the "xmlns" attribute, and any attribute with
   "xmlns:" as a 	prefix, is as specified in [XMLNS].  It is used to
   declare a namespace in XML.

   iCalendar provides for "experimental" elements.  These elements are
   represented in iCalendar with element names beginning with "X-".  Any
   experimental element in a	document which conforms to this memo MUST
   be represented by a namespace different than those used for
   iCalendar, iTIP, iMIP, or CAP.  This requirement is intended to
   simplify implementation of extensions and experimental items.



























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9.  Emailing documents with iCalendar XML Representation

   It is expected that iCalendar XML documents will need to be sent over
   SMTP/MIME email.  The "text/xml" and "application/xml" content-types
   have been registered for XML documents.

   All documents conforming to this memo SHOULD be sent as content-type
   "text/xml" or "application/xml".  When iCalendar elements may be
   mixed with others, it is not	practical for an MUA to determine,
   without opening the document, if iCalendar XML elements exist within
   the document.

   If a part of a MIME multi-part message contains only XML-represented
   iCalendar objects, and it is wished to provide the ability for an
   application to determine content based upon the MIME headers, the
   content-types "text/xml+calendar" or	"application/xml+calendar" MAY
   be used.

   Internet applications conforming to this memo MUST include in any
   iCalendar XML document that is sent, the XSL stylesheet reference to
   be used to provide transformation from the XML representation to the
   standard representation.  This	restriction guarantees that a standard
   iCalendar object can be produced from the iCalendar XML document.

   Internet applications conforming to this memo MAY send the iCalendar
   XML document in a "multipart/alternative" MIME entity that also
   contains an equivalent iCalendar object in the standard format
   defined by [RFC 2445], to provide compatibility with applications
   which cannot process XML or XSL transformations.

   An XML application comforming to the guidelines in this memo MUST be
   able to receive and properly process the "application/xml" document
   contained within a	"multipart" message content-type, and MUST be
   capable of performing the XSL transformation of the iCalendar
   elements of the document into a standard iCalendar document.
















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10.  iCalendar XML Representation and File Systems

   The iCalendar XML documents will be stored in file systems.  The
   accepted practice for file extensions for XML documents is the text
   "XML".  However, IF a document	contains only XML representations of
   iCalendar data, then for file association with applications that can
   directly process this document type, it is RECOMMENDED	that the file
   extension be the text "xcs".











































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11.  Example Usage

   The following sections provide various examples of documents using
   iCalendar elements in XML.

11.1  Example DTD

   The following is a DTD which can be used to represent iCalendar [RFC
   2445] objects.  While this DTD represents the iCalendar objects as
   currently defined, this document does not imply that this is the only
   way to represent them, nor that this is the best DTD to do so.  This
   is provided as an example, only.

   <?xml version="1.0" encoding="UTF-8"?>

      <!-- ******************* -->
      <!-- Entity declarations -->
      <!-- ******************* -->

      <!ENTITY % attr.altrep "
      altrep ENTITY #IMPLIED
      ">

      <!ENTITY % attr.cn "
      cn CDATA ''
      ">

      <!ENTITY % attr.cutype "
      cutype NMTOKEN 'INDIVIDUAL'
      ">
      <!-- Valid name tokens are "INDIVIDUAL", "GROUP", "RESOURCE" -->
      <!-- "ROOM", "UNKNOWN", a non-standard "X-" name or another -->
      <!-- IANA registered name. -->

      <!ENTITY % attr.delegated-from "
      delegated-from CDATA #IMPLIED
      ">
      <!-- delegated-from value is a calendar user address -->

      <!ENTITY % attr.delegated-to "
      delegated-to CDATA #IMPLIED
      ">
      <!-- delegated-to value is one or more calendar user addresses -->

      <!ENTITY % attr.dir "
      dir ENTITY #IMPLIED
      ">
      <!-- dir value is a URI to a directory entry -->



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      <!ENTITY % attr.fmttype "
      fmttype CDATA #REQUIRED
      ">
      <!-- fmttype value is any IANA registered content type -->

      <!ENTITY % attr.fbtype "
      fbtype NMTOKEN 'BUSY'
      ">

      <!-- Valid token values are "FREE", "BUSY", "BUSY-UNAVAILABLE", -->
      <!-- "BUSY-TENTATIVE", a non-standard "X-" name or another -->
      <!-- IANA registered name. -->

      <!ENTITY % attr.language "
      language CDATA #IMPLIED
      ">
      <!-- language value is a valid RFC 1766 language string -->

      <!ENTITY % attr.member "
      member CDATA #IMPLIED
      ">
      <!-- member value is one or more calendar user addresses -->

      <!ENTITY % attr.partstat "
      partstat NMTOKEN 'NEEDS-ACTION'
      ">
      <!-- Valid token value for VEVENT: "NEEDS-ACTION", "ACCEPTED", -->
      <!-- "DECLINED", "TENTATIVE", "DELEGATED", a non-standard "X- -->
      <!-- name or another IANA registered name. -->

      <!-- Valid token value for VTODO: "NEEDS-ACTION", "ACCEPTED", -->
      <!-- "DECLINED", "TENTATIVE", "DELEGATED", "COMPLETED", -->
      <!-- "IN-PROGRESS, a non-standard "X- name or another IANA -->
      <!-- registered name. -->
      <!-- Valid token value for VJOURNAL: "NEEDS-ACTION", "ACCEPTED", -->
      <!-- "DECLINED", a non-standard "X- name or another IANA -->
      <!-- registered name. -->

      <!ENTITY % attr.range "
      range NMTOKEN 'THISONLY'
      ">
      <!-- Valid token values are "THISONLY" or "THISANDPRIOR" or -->
      <!-- "THISANDFUTURE" -->

      <!ENTITY % attr.related "
      related NMTOKEN 'START'
      ">
      <!-- Valid token values are "START" or "END" -->



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      <!ENTITY % attr.reltype "
      reltype NMTOKEN 'PARENT'
      ">
      <!-- Valid token values are "PARENT", "CHILD", SIBLING", -->
      <!-- a non-standard "X-" name or any IANA registered name. -->

      <!ENTITY % attr.role "
      role NMTOKEN 'REQ-PARTICIPANT'
      ">

      <!-- Valid token values are "CHAIR", "REQ-PARTICIPANT", -->
      <!-- "OPT-PARTICIPANT", "NON-PARTICIPANT", a non-standard "X-" -->
      <!-- name or any IANA registered name. -->

      <!ENTITY % attr.rsvp "
      rsvp NMTOKEN 'FALSE'
      ">
      <!-- Valid token values are "TRUE" or "FALSE", -->

      <!ENTITY % attr.sent-by "
      sent-by CDATA #IMPLIED
      ">
      <!-- sent-by value is a calendar user address -->

      <!ENTITY % attr.tzid "
      tzid CDATA #IMPLIED
      ">
      <!-- tzid value is a time zone identifier -->

      <!ENTITY % cal.comp "
      vevent | vtodo | vjournal | vfreebusy | vtimezone
      ">

      <!ENTITY % vevent.opt1 "
      class | created | description | dtstamp | dtstart | geo |
      last-modified | location | organizer | priority | recurrence-id |
      sequence | status | summary | transp | uid | url |
      (dtend | duration)
      ">
      <!-- These properties may only appear once in a VEVENT -->
      <!ENTITY % vevent.optm "
      attach | attendee | categories | comment | contact |
      exdate | exrule | rdate | related-to | resources | request-status |
      rrule
      ">
      <!-- These properties may appear one or more times in a VEVENT -->

      <!ENTITY % vtodo.opt1 "



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      class | completed | created | description | dtstamp | dtstart |
      geo | last-modified | location | organizer | percent | priority |
      recurrence-id | sequence | status | summary | uid | url |
      (due | duration)
      ">
      <!-- These properties may only appear once in a VTODO -->

      <!ENTITY % vtodo.optm "
      attach | attendee | categories | comment | contact |
      exdate | exrule | request-status | related-to | resources |
      rdate | rrule

      ">
      <!-- These properties may appear one or more times in a VTODO -->

      <!ENTITY % vjournal.opt1 "
      class | created | description | dtstart | dtstamp | last-modified |
      organizer | recurrence-id | sequence | status | summary | uid | url
      ">
      <!-- These properties may only appear once in a VJOURNAL -->

      <!ENTITY % vjournal.optm "
      attach | attendee | categories | comment | contact |
      exdate | exrule | related-to | rdate | rrule | request-status
      ">
      <!-- These properties may appear one or more times in a VJOURNAL -->

      <!ENTITY % vfreebusy.opt1 "
      contact | dtstamp | dtstart | dtend | duration |
      organizer | uid | url
      ">
      <!-- These properties may only appear once in a VFREEBUSY -->

      <!ENTITY % vfreebusy.optm "
      attendee | comment | freebusy | request-status
      ">
      <!-- These properties may appear one or more times in a -->
      <!-- VFREEBUSY -->

      <!ENTITY % vtimezone.man "
      tzid
      ">
      <!-- These properties must appear in a VTIMEZONE -->

      <!ENTITY % vtimezone.opt1 "
      last-modified | tzurl
      ">
      <!-- These properties may only appear once in a VTIMEZONE -->



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      <!ENTITY % vtimezone.mann "
      (standard | daylight), (standard | daylight)*
      ">
      <!-- These properties must appear in a VTIMEZONE and may -->
      <!-- appear multiple times -->

      <!ENTITY % standard.man "
      dtstart | tzoffsetto | tzoffsetfrom
      ">
      <!-- These properties must appear in a STANDARD, but only once -->

      <!ENTITY % standard.optm "

      comment | rdate | rrule | tzname
      ">
      <!-- These properties may appear one or more times in a STANDARD -->

      <!ENTITY % daylight.man "
      dtstart | tzoffsetto | tzoffsetfrom
      ">
      <!-- These properties must appear in a DAYLIGHT, but only once -->

      <!ENTITY % daylight.optm "
      comment | rdate | rrule | tzname
      ">
      <!-- These properties may appear one or more times in a DAYLIGHT -->

      <!ENTITY % audio.man "
      action, trigger
      ">
      <!-- These properties must appear in an audio VALARM. -->

      <!ENTITY % audio.optx "
      duration | repeat
      ">
      <!-- These properties may appear once in an audio VALARM. If one -->
      <!-- appears, then both must appear. -->

      <!ENTITY % audio.opt1 "
      attach
      ">
      <!-- These properties may appear once in an audio VALARM. -->

      <!ENTITY % valarm.audio "
      (%audio.man;), (%audio.optx;)*, (%audio.opt1;)
      ">

      <!ENTITY % display.man "



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      action, description, trigger
      ">
      <!-- These properties must appear in a display VALARM. -->
      <!ENTITY % display.optx "
      duration | repeat
      ">
      <!-- These properties may appear once in a display VALARM. If -->
      <!-- one appears, then both must appear. -->

      <!ENTITY % valarm.display "
      (%display.man;), (%display.optx;)*
      ">

      <!ENTITY % email.man "

      action, description, summary, trigger
      ">
      <!-- These properties must appear in an email VALARM. -->

      <!ENTITY % email.optx "
      duration | repeat
      ">
      <!-- These properties may appear once in an email VALARM. If one -->
      <!-- appears, then both must appear. -->

      <!ENTITY % email.optm "
      attach
      ">
      <!-- These properties may appear one or more times in an email -->
      <!-- VALARM. -->

      <!ENTITY % email.mann "
      attendee
      ">
      <!-- These properties must appear in an email VALARM. The may -->
      <!-- appear more than once. -->

      <!ENTITY % valarm.email "
      (%email.man;), (%email.optx;)*, (%email.optm;)*,
      (%email.mann;)*
      ">

      <!ENTITY % procedure.man "
      action, attach, trigger
      ">
      <!-- These properties must appear in an audio VALARM. -->

      <!ENTITY % procedure.optx "



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      duration | repeat
      ">
      <!-- These properties may appear once in an procedure VALARM. -->
      <!-- If one appears, then both must appear. -->

      <!ENTITY % procedure.opt1 "
      description
      ">
      <!-- These properties may appear once in a procedure VALARM -->
      <!ENTITY % valarm.procedure "
      (%procedure.man;), (%procedure.optx;)*, (%procedure.opt1;)?
      ">

      <!-- ******************************************** -->
      <!-- iCalendar value type notation declarations   -->
      <!-- ******************************************** -->

      <!-- NOTE: The "XCAL" text in the following NOTATION values
      will be replaced with the text "RFC xxxx", where "xxxx" is the RFC
      number, when this memo is published as a RFC. -->

      <!NOTATION BINARY PUBLIC "-//IETF//NOTATION XCAL/Value Type/Binary//EN">

      <!NOTATION BOOLEAN PUBLIC "-//IETF//NOTATION XCAL/Value Type/Boolean//EN">

      <!NOTATION CALADR PUBLIC "-//IETF//NOTATION XCAL/Value Type/Calendar
      User Address//EN">

      <!NOTATION DATE PUBLIC "-//IETF//NOTATION XCAL/Value Type/Date//EN">

      <!NOTATION DATE-TIME PUBLIC "-//IETF//NOTATION XCAL/Value
      Type/Date-Time//EN">

      <!NOTATION DURATION PUBLIC "-//IETF//NOTATION XCAL/Value
      Type/Duration//EN">

      <!NOTATION FLOAT PUBLIC "-//IETF//NOTATION XCAL/Value Type/Float//EN">

      <!NOTATION INTEGER PUBLIC "-//IETF//NOTATION XCAL/Value Type/Integer//EN">

      <!NOTATION PERIOD PUBLIC "-//IETF//NOTATION XCAL/Value
      Type/Period of Time//EN">

      <!NOTATION RECUR PUBLIC "-//IETF//NOTATION XCAL/Value
      Type/Recurrence Rule//EN">

      <!NOTATION TEXT PUBLIC "-//IETF//NOTATION XCAL/Value Type/Text//EN">




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      <!NOTATION TIME PUBLIC "-//IETF//NOTATION XCAL/Value Type/Time//EN">

      <!NOTATION URI PUBLIC "-//IETF//NOTATION XCAL/Value Type/URI//EN">

      <!NOTATION UTC-OFFSET PUBLIC "-//IETF//NOTATION XCAL/Value
      Type/UTC-Offset//EN">

      <!NOTATION X-NAME PUBLIC "-//IETF//NOTATION XCAL/Value Type/X-Name//EN">

      <!-- ************************************************* -->
      <!-- iCalendar property element/attribute declarations -->
      <!-- ************************************************* -->

      <!ELEMENT br EMPTY>
      <!-- Signifies a new line in the TEXT value content information -->

      <!-- Description component properties element type declarations -->

      <!ELEMENT attach (extref | b64bin)>
      <!-- extref holds a reference to an external entity that -->
      <!-- has the attachment. b64bin holds the inline BASE64 encoded -->
      <!-- binary data for the attachment as defined in RFC 2045. -->

      <!ELEMENT extref EMPTY>
      <!ATTLIST extref
      uri ENTITY #REQUIRED>

      <!ELEMENT b64bin (#PCDATA)>
      <!ATTLIST b64bin
      %attr.fmttype;
      value NOTATION (BINARY) #IMPLIED>

      <!ELEMENT categories (item)*>

      <!ELEMENT item (#PCDATA)>
      <!ATTLIST item
      %attr.language;
      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT class (#PCDATA)>
      <!ATTLIST class
      %attr.language;
      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT comment (#PCDATA)*>
      <!ATTLIST comment
      %attr.language;
      %attr.altrep;



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      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT description (#PCDATA)*>
      <!ATTLIST description
      %attr.language;
      %attr.altrep;
      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT geo (lat, lon)>

      <!ELEMENT lat (#PCDATA)>
      <!ATTLIST lat value NOTATION (FLOAT) #IMPLIED>
      <!-- A decimal degree float number to 6 decimal places -->

      <!ELEMENT lon (#PCDATA)>
      <!ATTLIST lon value NOTATION (FLOAT) #IMPLIED>
      <!-- A decimal degree float number to 6 decimal places -->

      <!ELEMENT location (#PCDATA)>
      <!ATTLIST location
      %attr.language;
      %attr.altrep;
      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT percent (#PCDATA)>
      <!ATTLIST percent
      value NOTATION (INTEGER) #IMPLIED>

      <!ELEMENT priority (#PCDATA)>
      <!ATTLIST priority
      value NOTATION (INTEGER) #IMPLIED>

      <!ELEMENT resources (#PCDATA)>
      <!ATTLIST resources
      %attr.language;
      %attr.altrep;
      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT status (#PCDATA)>
      <!ATTLIST status
      %attr.language;
      %attr.altrep;
      value NOTATION (TEXT) #IMPLIED>
      <!-- Text value must match the valid values for the particular -->
      <!-- calendar component. -->

      <!ELEMENT summary (#PCDATA)>
      <!ATTLIST summary



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      %attr.language;
      %attr.altrep;
      value NOTATION (TEXT) #IMPLIED >

      <!-- Data and time component property element type declarations -->

      <!ELEMENT dtstart (#PCDATA)>
      <!ATTLIST dtstart
      %attr.tzid;
      value NOTATION (DATE-TIME | DATE) "DATE-TIME">

      <!ELEMENT dtend (#PCDATA)>
      <!ATTLIST dtend
      %attr.tzid;
      value NOTATION (DATE-TIME | DATE) "DATE-TIME">

      <!ELEMENT due (#PCDATA)>
      <!ATTLIST due
      %attr.tzid;
      value NOTATION (DATE-TIME | DATE) "DATE-TIME">

      <!ELEMENT completed (#PCDATA)>
      <!ATTLIST completed
      value NOTATION (DATE-TIME) #IMPLIED>

      <!ELEMENT duration (#PCDATA)>
      <!ATTLIST duration
      value NOTATION (DURATION) #IMPLIED>

      <!ELEMENT freebusy (#PCDATA)>
      <!ATTLIST freebusy
      %attr.fbtype;
      value NOTATION (PERIOD) #IMPLIED>

      <!ELEMENT transp (#PCDATA)>
      <!ATTLIST transp
      value NOTATION (TEXT) #IMPLIED>
      <!-- Text value must be one of the valid enumerations. -->

      <!-- Time zone component property element type declarations -->

      <!ELEMENT tzid (#PCDATA)>
      <!ATTLIST tzid
      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT tzname (#PCDATA)>
      <!ATTLIST tzname
      %attr.language;



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      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT tzoffsetfrom (#PCDATA)>
      <!ATTLIST tzoffsetfrom
      value NOTATION (UTC-OFFSET) #IMPLIED>

      <!ELEMENT tzoffsetto (#PCDATA)>
      <!ATTLIST tzoffsetto
      value NOTATION (UTC-OFFSET) #IMPLIED>

      <!ELEMENT tzurl EMPTY>
      <!ATTLIST tzurl
      uri ENTITY #REQUIRED>

      <!-- Relationship component property element type declarations -->

      <!ELEMENT attendee (#PCDATA)>
      <!ATTLIST attendee
      %attr.language;
      %attr.cn;
      %attr.role;
      %attr.partstat;
      %attr.rsvp;
      %attr.cutype;
      %attr.member;
      %attr.delegated-to;
      %attr.delegated-from;
      %attr.sent-by;
      %attr.dir;
      value NOTATION (CALADR) #IMPLIED>

      <!ELEMENT contact (#PCDATA)*>
      <!ATTLIST contact
      %attr.language;
      %attr.altrep;
      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT organizer (#PCDATA)>
      <!ATTLIST organizer
      %attr.language;
      %attr.cn;
      %attr.sent-by;
      %attr.dir;
      value NOTATION (CALADR) #IMPLIED>

      <!ELEMENT recurrence-id (#PCDATA)>
      <!ATTLIST recurrence-id
      %attr.tzid;



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      %attr.range;
      value NOTATION (DATE-TIME | DATE) "DATE-TIME">

      <!ELEMENT related-to (#PCDATA)>
      <!ATTLIST related-to
      %attr.reltype;
      value NOTATION (TEXT) #IMPLIED>

      <!ELEMENT url EMPTY>
      <!ATTLIST url
      uri ENTITY #REQUIRED>

      <!ELEMENT uid (#PCDATA)>
      <!ATTLIST uid
      value NOTATION (TEXT) #IMPLIED>

      <!-- Recurrence component property element type declarations -->

      <!ELEMENT exdate (#PCDATA)>
      <!ATTLIST exdate
      %attr.tzid;
      value NOTATION (DATE-TIME | DATE) "DATE-TIME">

      <!ELEMENT exrule (#PCDATA)>
      <!ATTLIST exrule
      value NOTATION (RECUR) #IMPLIED>

      <!ELEMENT rdate (#PCDATA)>
      <!ATTLIST rdate
      %attr.tzid;
      value NOTATION (DATE-TIME | DATE) "DATE-TIME">

      <!ELEMENT rrule (#PCDATA)>
      <!ATTLIST rrule
      value NOTATION (RECUR) #IMPLIED>

      <!-- Alarm component property element type declarations -->

      <!ELEMENT action (#PCDATA)>
      <!ATTLIST action
      value NOTATION (TEXT) #IMPLIED>
      <!-- Text value must be a valid enumeration -->

      <!ELEMENT repeat (#PCDATA)>
      <!ATTLIST repeat
      value NOTATION (INTEGER) #IMPLIED>

      <!ELEMENT trigger (#PCDATA)>



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      <!ATTLIST trigger
      %attr.related-to;
      value NOTATION (DURATION | DATE-TIME) "DURATION">

      <!-- Change management component property element type -->
      <!-- declarations -->

      <!ELEMENT created (#PCDATA)>
      <!ATTLIST created
      value NOTATION (DATE-TIME) #IMPLIED>

      <!ELEMENT dtstamp (#PCDATA)>
      <!ATTLIST dtstamp
      value NOTATION (DATE-TIME) #IMPLIED>

      <!ELEMENT last-modified (#PCDATA)>
      <!ATTLIST last-modified
      value NOTATION (DATE-TIME) #IMPLIED>

      <!ELEMENT sequence (#PCDATA)>
      <!ATTLIST sequence
      value NOTATION (INTEGER) #IMPLIED>

      <!-- Miscellaneous component property element type declarations -->

      <!ELEMENT request-status (#PCDATA)>
      <!ATTLIST request-status
      %attr.language;
      value NOTATION (TEXT) #IMPLIED>

      <!-- iCalendar object element type declarations -->

      <!ELEMENT iCalendar (vcalendar+)>

      <!ELEMENT vcalendar (%cal.comp;)*>
      <!ATTLIST vcalendar
      %attr.language;
      xmlns CDATA #FIXED 'http://www.ietf.org/internet-drafts/draft-
      hare-xcalendar-01.txt'
      calscale CDATA "GREGORIAN"
      method CDATA "PUBLISH"
      version CDATA #REQUIRED
      prodid CDATA #IMPLIED>
      <!-- version - Must be "2.0" if document conforms to this spec. -->
      <!-- calscale - Calendar scale. Default is GREGORIAN. -->
      <!-- method - C&S method. Default is iTIP PUBLISH. -->
      <!-- prodid - ISO 9070 FPI for product that generated iCalendar. -->




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      <!-- "vevent" element type declaration -->
      <!ELEMENT vevent ((%vevent.opt1;)*, (%vevent.optm;)*, valarm*)>

      <!-- "vtodo" element type declaration -->
      <!ELEMENT vtodo ((%vtodo.opt1;)*, (%vtodo.optm;)*, valarm*)>

      <!-- "vjournal" element type declaration -->
      <!ELEMENT vjournal ((%vjournal.opt1;)*, (%vjournal.optm;)*)>

      <!-- "vfreebusy" element type declaration -->
      <!ELEMENT vfreebusy ((%vfreebusy.opt1;)*, (%vfreebusy.optm;)*)>

      <!-- "vtimezone" element type declaration -->
      <!ELEMENT vtimezone (%vtimezone.man;, (%vtimezone.opt1;)*,
      (%vtimezone.mann;)*)>

      <!ELEMENT standard (((%standard.man;)*), (%standard.optm;)*)>

      <!ELEMENT daylight (((%daylight.man;)*), (%daylight.optm;)*)>

      <!ELEMENT valarm ((%valarm.audio;) | (%valarm.display;) |
      (%valarm.email;) | (%valarm.procedure;))>




11.2  An example XSL transformation

   The following is an example of an XSL transformation which can
   convert an xCalendar document into an iCalendar [RFC 2445] text
   object.  Again, this is an 	example and not presented as the only or
   best way to accomplish the 	transformation.

   <?xml version="1.0" encoding="UTF-8"?>
   <xsl:stylesheet version="1.0"
           xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
           xmlns:ical="http://www.ietf.org/rfc/rfc2445.txt"
           xmlns:itip="http://www.ietf.org/rfc/rfc2446.txt"
           xmlns="http://www.ietf.org/rfc/rcf2445.txt">
   <!-- ======================================================================== -->
   <!-- xcal2ics.xsl XSL transformation of xCalendar documents to iCalendar file -->
   <!-- Tim Hare, April 2004                                                     -->
   <!-- Tim Hare, August 2004 -  updated to wrap at 75 chars                     -->
   <!-- Tim Hare, November 2004 - removed unused template, cleanup               -->
   <!-- Tim Hare, May 2005 - added function to quote some characters             -->
   <!-- This transformation may be freely used, attribution is appreciated       -->
   <!-- Concepts and inspiration due to rdf2ical from Masahide Kanzaki           -->
   <!-- who should also receive attribution                                      -->



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   <!-- ======================================================================== -->
   <!-- define output format for iCalendar for use in result-document instr.     -->
   <xsl:output method="text" media-type="text/calendar" />
   <xsl:template match="icalendar|iCalendar|ical:icalendar|ical:iCalendar">
           <xsl:apply-templates select="vcalendar|ical:vcalendar" />
   </xsl:template>
   <xsl:template match="vcalendar|ical:vcalendar">
                   <xsl:call-template name="emit_text">
                   <!-- parameter "line" is entire result of here to end of with-param -->
                   <xsl:with-param name="line">
                           <xsl:text>BEGIN:VCALENDAR</xsl:text>
                   </xsl:with-param>
                   </xsl:call-template>
                           <xsl:if test="not(@method) and
                                   not(@Method) and
                                     not(@ical:method) and
                                             not(@ical:Method)">
                                   <xsl:call-template name="emit_text">
                                   <xsl:with-param name="line">
                                           <xsl:text>METHOD:PUBLISH</xsl:text>
                                   </xsl:with-param>
                                   </xsl:call-template>
                           </xsl:if>
                           <xsl:for-each select="@*">
                                   <xsl:call-template name="emit_text">
                                   <xsl:with-param name="line">
                                           <xsl:call-template name="stringcap">
                                           <xsl:with-param name="s" select="local-name()" />
                                           </xsl:call-template>
                                           <xsl:text>:</xsl:text>
                                           <xsl:call-template name="stringcap">
                                           <xsl:with-param name="s" select="current()" />
                                           </xsl:call-template>
                                   </xsl:with-param>
                                   </xsl:call-template>
                           </xsl:for-each>
                   <xsl:apply-templates select="./*" />
                   <xsl:call-template name="emit_text">
                   <xsl:with-param name="line">
                           <xsl:text>END:VCALENDAR</xsl:text>
                   </xsl:with-param>
                   </xsl:call-template>
   </xsl:template>
   <xsl:template name="eachcomponent"      match="vevent|vtodo|vjournal|valarm|ical:vevent|ical:vtodo|ical:vjournal|ical:valarm">
           <xsl:call-template name="emit_text">
           <xsl:with-param name="line">
                   <xsl:text>BEGIN:</xsl:text>
                   <xsl:call-template name="stringcap">



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                   <xsl:with-param name="s" select="local-name()" />
                   </xsl:call-template>
           </xsl:with-param>
           </xsl:call-template>
                   <xsl:for-each select="./*" >
                                   <xsl:call-template name="eachproperty" />
                   </xsl:for-each>
                   <xsl:call-template name="emit_text">
                   <xsl:with-param name="line">
                           <xsl:text>END:</xsl:text>
                           <xsl:call-template name="stringcap">
                           <xsl:with-param name="s" select="local-name()" />
                           </xsl:call-template>
                   </xsl:with-param>
                   </xsl:call-template>
   </xsl:template>
   <xsl:template name="eachproperty">
           <xsl:if test="local-name() != 'categories' and
                             local-name() != 'CATEGORIES' and
                             local-name() != 'geo' and
                             local-name() != 'GEO' and
                             local-name() != 'resources' and
                             local-name() != 'RESOURCES'">
           <!-- this block outputs a property with all of its parameters -->
                   <xsl:call-template name="emit_text">
                   <xsl:with-param name="line">
                           <xsl:call-template name="stringcap">
                           <xsl:with-param name="s" select="local-name()" />
                           </xsl:call-template>
                           <xsl:for-each select="@*">
                                   <xsl:call-template name="eachparam">
                                   <xsl:with-param name="p" select="local-name()" />
                                   </xsl:call-template>
                           </xsl:for-each>
                           <xsl:text>:</xsl:text>
                           <!-- call replace-text to quote newline, semicolon, colon, reverse solidus, and comma -->
                           <xsl:call-template name="quote-some">
                           <xsl:with-param name="text"><xsl:value-of select="." /></xsl:with-param>
                     </xsl:call-template>
                   </xsl:with-param>
                   </xsl:call-template>
           <!-- end of regular properties ouput block                     -->
           </xsl:if>
           <xsl:if test="local-name() = 'categories' or
                             local-name() = 'CATEGORIES' or
                             local-name() = 'resources' or
                             local-name() = 'RESOURCES'">
           <!-- this block outputs a Categories or Resources property     -->



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                   <xsl:call-template name="emit_text">
                   <xsl:with-param name="line">
                           <xsl:call-template name="stringcap">
                                   <xsl:with-param name="s" select="local-name()" />
                           </xsl:call-template>
                           <xsl:for-each select="@*">
                                   <xsl:call-template name="eachparam">
                                   <xsl:with-param name="p" select="local-name()" />
                                   </xsl:call-template>
                           </xsl:for-each>
                           <xsl:text>:</xsl:text>
                           <xsl:for-each select="./item|./ITEM">
                                   <xsl:call-template name="stringcap">
                                   <xsl:with-param name="s" select="current()" />
                                   </xsl:call-template>
                                   <xsl:if test="position() != last()">
                                           <xsl:text>,</xsl:text>
                                   </xsl:if>
                           </xsl:for-each>
                   </xsl:with-param>
                   </xsl:call-template>
           <!-- end of Categories or Resources property output block       -->
           </xsl:if>
           <xsl:if test="local-name() = 'geo' or
                             local-name() = 'GEO'">
           <!-- this block outputs a Geo property                          -->
                   <xsl:call-template name="emit_text">
                   <xsl:with-param name="line">
                           <xsl:call-template name="stringcap">
                           <xsl:with-param name="s" select="local-name()" />
                           </xsl:call-template>
                           <xsl:text>:</xsl:text>
                           <xsl:value-of select="lat" />
                           <xsl:text>;</xsl:text>
                           <xsl:value-of select="lon" />
                   </xsl:with-param>
                   </xsl:call-template>
           <!-- end of Geo property output block                            -->
           </xsl:if>
   </xsl:template>
   <xsl:template name="eachparam">
           <xsl:param name="p" />
           <xsl:text>;</xsl:text>
           <xsl:call-template name="stringcap">
                   <xsl:with-param name="s" select="string($p)"/>
           </xsl:call-template>
           <xsl:text>=</xsl:text>
           <xsl:value-of select="." />



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   </xsl:template>
   <!-- Capitalize and output a string -->
   <xsl:template name="stringcap">
   <xsl:param name="s"/>
   <xsl:value-of select="translate($s,'abcdefghijklmnopqrstuvwxyz','ABCDEFGHIJKLMNOPQRSTUVWXYZ')"/>
   </xsl:template>
   <!-- Emit text, 75 character max per line, recursively -->
   <xsl:template name="emit_text">
           <xsl:param name="limit" select="number(75)"/> <!-- default limit is 75 " -->
           <xsl:param name="line"/>
           <xsl:value-of select="substring(normalize-space($line),1,$limit)" />
           <!-- Output the newline string -->
           <xsl:text>&#13;&#10;</xsl:text>
           <xsl:if test="string-length($line) > $limit">
                   <xsl:text> </xsl:text>
                   <xsl:call-template name="emit_text">
                           <xsl:with-param name="limit" select="($limit - 1)" /> <!-- use 74 allow for space -->
                           <xsl:with-param name="line" select="substring($line,($limit + 1))" />
                   </xsl:call-template>
           </xsl:if>
   </xsl:template>
   <!-- ACK: ASPN replace-string function used to model this
     http://aspn.activestate.com/ASPN/Cookbook/XSLT/Recipe/65426
     via Dan Connolly, W3C

     all characters to be quoted are in this template rather than doing multiple calls to the template
     in the hopes that this will improve performance.
     -->
   <xsl:template name="quote-some">
       <!-- rfc2445#sec4.3.11 says to quote DQUOTE, newline, semicolon, colon,
                              reverse solidus, comma -->
       <xsl:param name="text">
       <xsl:choose>
         <xsl:when test="contains($text,'&quot')">
           <xsl:variable name="before" select="substring-before($text,'&quot')
           <xsl:variable name="before" select="substring-after($text,'&quot')/>
           <xsl:value-of select="$before"/>
           <xsl:value-of select="\&quot" />
           <xsl:call-template name="quote-some">
           <xsl:with-param name="text" select="&after" />
           </xsl:call-template>
         </xsl:when>
         <xsl:when test="contains($text,'&#10')">
           <xsl:variable name="before" select="substring-before($text,'&#10')
           <xsl:variable name="before" select="substring-after($text,'&#10')/>
           <xsl:value-of select="$before"/>
           <xsl:value-of select="\n" />
           <xsl:call-template name="quote-some">



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           <xsl:with-param name="text" select="&after" />
           </xsl:call-template>
         </xsl:when>
         <xsl:when test="contains($text,';')">
           <xsl:variable name="before" select="substring-before($text,';')/>
           <xsl:variable name="before" select="substring-after($text,';')/>
           <xsl:value-of select="$before"/>
           <xsl:value-of select="\;" />
           <xsl:call-template name="quote-some">
           <xsl:with-param name="text" select="&after" />
           </xsl:call-template>
          </xsl:when>
         <xsl:when test="contains($text,':')">
           <xsl:variable name="before" select="substring-before($text,':')/>
           <xsl:variable name="before" select="substring-after($text,':')/>
           <xsl:value-of select="$before"/>
           <xsl:value-of select="\:" />
           <xsl:call-template name="quote-some">
           <xsl:with-param name="text" select="&after" />
           </xsl:call-template>
          </xsl:when>
         <xsl:when test="contains($text,'\')">
           <xsl:variable name="before" select="substring-before($text,'\')/>
           <xsl:variable name="before" select="substring-after($text,'\')/>
           <xsl:value-of select="$before"/>
           <xsl:value-of select="\\" />
           <xsl:call-template name="quote-some">
           <xsl:with-param name="text" select="&after" />
           </xsl:call-template>
          </xsl:when>
         <xsl:when test="contains($text,',')">
           <xsl:variable name="before" select="substring-before($text,',')/>
           <xsl:variable name="before" select="substring-after($text,',')/>
           <xsl:value-of select="$before"/>
           <xsl:value-of select="\," />
           <xsl:call-template name="quote-some">
           <xsl:with-param name="text" select="&after" />
           </xsl:call-template>
          </xsl:when>
       <xsl:otherwise>
           <xsl:value-of select="$text"/>
       </xsl:otherwise>
       </xsl:choose>
    </xsl:template>
   </xsl:stylesheet>






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11.3  A well-formed and valid iCalendar XML document

   The following is a simple example of a iCalendar XML document.  This
   document is both a well-formed and valid XML document.  It also
   contains the required reference to the XSL transformation.  The
   iCalendar object specifies an appointment.

         <?xml version="1.0" encoding="UTF-8"?>
         <!DOCTYPE iCalendar PUBLIC "-//IETF//DTD XCAL/iCalendar XML//EN"
         "http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt">
         <?xml-stylesheet href="xcal2ics.xsl" type="text/xsl" output="text" ?>
         <iCalendar>
         <vcalendar method="PUBLISH"
               version="2.0"
               prodid="-//HandGen//NONSGML vGen v1.0//EN">
         <vevent>
              <uid>19981116T150000@cal10.host.com</uid>
              <dtstamp>19981116T145958Z</dtstamp>
              <summary>Project XYZ Review</summary>
              <location>Conference Room 23A</location>
              <dtstart>19981116T163000Z</dtstart>
              <dtend>19981116T190000Z</dtend>
              <categories>
                   <item>Appointment</item>
              </categories>
         </vevent>
         </vcalendar>
         </iCalendar>


11.4  Including binary content in attachments

   The following is an example of a valid iCalendar XML document that
   also	includes an external reference to an attachment.  The iCalendar
   object specifies	a meeting invitation with an attachment.
















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      <?xml version="1.0" encoding="UTF-8"?>
      <!DOCTYPE iCalendar PUBLIC "-//IETF//DTD XCAL/iCalendar XML//EN"
      "http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt"
      <?xml-stylesheet href="xcal2ics.xsl" type="text/xsl" output="text" ?>

      <iCalendar>
       <vcalendar>
        <method>REQUEST</method>
        <version>2.0</version>
        <prodid>-//HandGen//NONSGML vGen v1.0//EN</prodid>
        <vevent>
         <uid>19981211T133000@cal1.host.com</uid>
         <dtstamp>19981211T132928Z</dtstamp>
         <organizer>cap://host.com/jim</organizer>
         <dtstart>19981212T150000Z</dtstart>
         <dtend>19981212T160000Z</dtend>
         <summary>Department Meeting</summary>
         <location>Conference Room 23A</location>
         <attendee role="CHAIR">jim@host.com</attendee>
         <attendee role="REQ-PART"
                   rsvp="TRUE">MAILTO:joe@host.com</attendee>
         <attendee role="REQ-PART"
                   rsvp="TRUE">MAILTO:steve@host.com</attendee>
         <attach>http://host.com/pub/photos/holiday.jpg</attach>
        </vevent>
       </vcalendar>
      </iCalendar>


11.5  Including binary content inline

   The following is an example of a well-formed and valid iCalendar XML
   document that includes an attachment as inline binary content.  The
   iCalendar	object specifies a meeting invitation with an attachment.

















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      <?xml version="1.0" encoding="UTF-8"?>
      <!DOCTYPE iCalendar PUBLIC "-//IETF//DTD XCAL/iCalendar XML//EN"
      "http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt">
      <?xml-stylesheet href="xcal2ics.xsl" type="text/xsl" output="text" ?>
      <iCalendar>
      <vcalendar>
       <method>REQUEST</method>
       <version>2.0</version>
       <prodid>-//HandGen//NONSGML vGen v1.0//EN</prodid>
       <vevent>
        <uid>19981211T133000@cal1.host.com</uid>
        <dtstamp>19981211T132928Z</dtstamp>
        <organizer>MAILTO:jim@host.com</organizer>
        <dtstart>19981212T150000Z</dtstart>
        <dtend>19981212T160000Z</dtend>
        <summary>Department Meeting</summary>
        <location>Conference Room 23A</location>
        <attendee role="CHAIR">MAILTO:jim@host.com</attendee>
        <attendee role="REQ-PART"
                  rsvp="TRUE">MAILTO:joe@host.com</attendee>
        <attendee role="REQ-PART"
                  rsvp="TRUE">MAILTO:steve@host.com</attendee>
        <attach fmttype="IMAGE/JPEG">MIICajCCAdOgAwIBAgI
        CBEUwDQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXB
        lIEjYXRpb25z...and so on...IENvcnBvc==</attach>
       </vevent>
       </vcalendar>
      </iCalendar>


11.6  iCalendar XML document with multiple iCalendar objects

   The following is an example of a well-formed and valid iCalendar XML
   document that includes more than one iCalendar object.

















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      <?xml version="1.0" encoding="UTF-8"?>
      <!DOCTYPE iCalendar PUBLIC "-//IETF//DTD XCAL/iCalendar XML//EN"
      "http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt">
      <?xml-stylesheet href="xcal2ics.xsl" type="text/xsl" output="text" ?>
      <iCalendar annotation="IT Conference Prep">
      <vcalendar>
       <method>PUBLISH</method>
       <version>2.0</version>
       <prodid>-//HandGen//NONSGML vGen v1.0//EN</prodid>
       <vtodo>
        <uid>19981009T233000@cal1.host.com</uid>
        <dtstamp>19981009T232928Z</dtstamp>
        <dtstart>19981010T000000Z</dtstart>
        <due>19981010T235959Z</due>
        <summary>Register for conference</summary>
        <priority>2</priority>
       </vtodo>
      </vcalendar>
      <vcalendar>
       <version>2.0</version>
       <prodid>-//HandGen//NONSGML vGen v1.0//EN</prodid>
       <method>PUBLISH</method>
       <vevent>
        <uid>19981009T233010@cal1.host.com</uid>
        <dtstamp>19981009T233000Z</dtstamp>
        <dtstart>19981120T133000Z</dtstart>
        <dtend>19981122T183000Z</dtend>
        <summary>IT Conference</summary>
        <location>Downtowner Hotel</location>
       </vevent>
      </vcalendar>
      </iCalendar>


11.7  Using the iCalendar namespace

   The following is an example of a snippet of a XML document that
   includes elements from the iCalendar name-space.

      <x xmlns:xcal="http://www.ietf.org/internet-drafts/
      draft-hare-xcalendar-01.txt"
      xmlns:pdi="http://pdi.org/schema">
      <xcal:dtstart>19981123T133000Z</xcal:dtstart>
      <xcal:dtend>19981123T203000Z</xcal:dtend>
      <pdi:idnum>1234567</pdi:idnum>
      <pdi:usage>999.99</pdi:usage>
      </x>




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11.8  Publish meeting information

   The following is a snippet of an iCalendar XML document that
   publishes information about a meeting.

      <iCalendar>
       <vcalendar>
        <version>2.0</version>
        <prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
        <method>PUBLISH</method>
        <vevent>
         <uid>19970901T130000Z-123401@host.com</uid>
         <dtstamp>19970901T130000Z</dtstamp>
         <dtstart>19970903T163000Z</dtstart>
         <dtend>19970903T190000Z</dtend>
         <summary>Annual Employee Review</summary>
         <class>PRIVATE</class>
         <categories>Business,Human Resources</categories>
        </vevent>
       </vcalendar>
      </iCalendar>


11.9  Publish transparent annual event

   The following is a snippet of an iCalendar XML document that
   publishes information about an annually repeating event that is
   transparent to busy time searches.

      <iCalendar>
       <vcalendar>
        <version>2.0</version>
        <prodid-//hacksw/handcal//NONSGML 1.0//EN</prodid>
        <method>PUBLISH</publish>
        <vevent>
         <uid>19990101T125957Z-123403@host.com</uid>
         <dtstamp>19990101T130000Z</dtstamp>
         <dtstart value="DATE">19991102</dtstart>
         <summary>Our Blissful Anniversary</summary>
         <class>CONFIDENTIAL</class>
         <transp>TRANSPARENT</transp>
         <categories>Anniversary,Personal,Special Occasion</categories>
         <rrule>FREQ=YEARLY</rrule>
        </vevent>
       </vcalendar>
      </iCalendar>





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11.10  Meeting invitation

   The following is a snippet of an iCalendar XML document that
   specifies an invitation for a meeting.  The meeting occurs on the
   first Monday of each year for five years.

      <iCalendar>
       <vcalendar>
       <method>REQUEST</method>
       <version>2.0</version>
       <prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
       <vevent>
        <uid>19981220T130000Z-123403@host.com</uid>
        <dtstamp>19981220T130050Z</dtstamp>
        <organizer>MAILTO:corprel@host.com</organizer>
        <dtstart>19990104T140000Z</dtstart>
        <dtend>19990104T220000Z</dtend>
        <summary>Annual Stockholders Meeting</summary>
        <location>One Corporate Drive, Wilmington, DL</location>
        <attendee role="CHAIR">MAILTO:mrbig@host.com</attendee>
        <attendee cutype="GROUP"
                  rsvp="TRUE">CAP:host.com/stockholders</attendee>
        <categories>Business,Meeting,Special Occasion</categories>
        <rrule>FREQ=YEARLY;COUNT=5;BYDAY=1MO</rrule>
        </vevent>
       </vcalendar>
      </iCalendar>


11.11  Assign a to-do

   The following is a snippet of an iCalendar XML document for a to-do.



















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      <iCalendar>
       <vcalendar>
        <method>REQUEST</method>
        <version>2.0</version>
        <prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
        <vtodo>
         <uid>19990104T133402@ical1.host.com</uid>
         <dtstamp>19990104T133410Z</dtstamp>
         <dtstart value="DATE">19990104</dtstart>
         <due value="DATE">19990129</due>
         <organizer>MAILTO:dboss@host.com</organizer>
         <summary>Periodic Self Review</summary>
         <description>Complete your self review.
         Contact me if you questions.</description>
         <priority>1</priority>
         <class>CONFIDENTIAL</class>
         <attendee>CAP:dilbert@host.com</attendee>
        </vtodo>
       </vcalendar>
      </iCalendar>


11.12  Publish busy time

   The following is an iCalendar XML document that publishes busy time
   information.  The default value for the "method" attribute is
   "PUBLISH" and does	not need to be specified in this example.



      <iCalendar>
       <vcalendar>
        <version>2.0</version>
        <prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
        <vfreebusy>
         <uid>19980313T133000@ical1.host.com</uid>
         <dtstamp>19990104T133010Z</dtstamp>
         <organizer>CAP:host.com/jsmith</organizer>
         <dtstart>19980313T141711Z</dtstart>
         <dtend>19980410T141711Z</dtend>
         <url>jsmith.ifb</url>
         <freebusy>19980314T233000Z/19980315T003000Z</freebusy>
         <freebusy>19980316T153000Z/19980316T163000Z</freebusy>
         <freebusy>19980318T030000Z/19980318T040000Z</freebusy>
        </vfreebusy>
       </vcalendar>
      </iCalendar>




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11.13  Request busy time

   The following is a snippet of an iCalendar XML document that requests
   a calendar user's busy time information.

      <iCalendar>
       <vcalendar>
        <method>REQUEST</method>
        <version>2.0</version>
        <prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
        <vfreebusy>
         <uid>19970901T083000@ical1.host.com</uid>
         <dtstamp>19970901T083000Z</dtstamp>
         <organizer>MAILTO:jane_doe@host1.com</organizer>
         <dtstart>19971015T050000Z</dtstart>
         <dtend>19971016T050000Z</dtend>
         <attendee>MAILTO:john_public@host2.com</attendee>
        </vfreebusy>
       </vcalendar>
      </iCalendar>


11.14  Issue a CAP command

   The following is a snippet of an iCalendar XML document that issues a
   CAP	command to delete a UID.

      <iCalendar xmlns="http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt"
                     xmlns:CAP="="http://www.ietf.org/internet-drafts/draft-ietf-calsch-cap-13.txt">
       <vcalendar>
        <version>2.0</version>
        <prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
        <target>relcalid-22</target>
        <CAP:cmd id="random but unique per CUA">DELETE</CAP:cmd>
        <CAP:vquery>
         <CAP:query>SELECT VEVENT FROM VAGENDA WHERE UID = 'abcd12345'</CAP:query>
        </CAP:vquery>
        </vcalendar>
       </iCalendar>


11.15  A well-formed and valid XML document which can be transformed
       into iCalendar

   The following is a simple example document which contains some date
   and time elements .  This document is both a well-formed and valid
   XML document.  It contains a DTD and references a stylesheet which
   transforms the schedule elements into iCalendar.  The time used is a



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   "floating" time, without timezone information, to simplify the
   example.

      <?xml version="1.0" encoding="UTF-8"?>
      <!DOCTYPE tour [
           <!ELEMENT tourdata (performer,tourname,gig+)>
           <!ELEMENT performer (#PCDATA)>
           <!ELEMENT tourname (#PCDATA)>
           <!ELEMENT gig (venue,date,time)>
           <!ELEMENT venue (#PCDATA)>
           <!ELEMENT date (#PCDATA)>
           <!ELEMENT time (#PCDATA)]>
      <?xml-stylesheet type="text/xsl" href="tour2ical.xsl" output="text">
           <tour>
           <performer>Frank Dylan</performer>
           <tourname>Rolling Blunder Revue</tourname>
           <gig>
                   <venue>East Sandusky, Ohio Civic Auditorium</venue>
                   <date>01/03/1997</date>
                   <time>21:00:00</time>
           </gig>
           <gig>
                   <venue>Sandlot, NM Lost Highway Cafe</venue>
                   <date>08/09/1997</date>
                   <time>12:00:00</time>
           </gig>
           </tour>

   The required stylesheet to transform the document into an iCalendar
   object (tour2ical.xsl) .  Note that some of the transformations,
   notably date and time,	would need more work to provide the robustness
   usually needed for applications;	the simple method here is used as an
   example only.


















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             <?xml version="1.0" encoding="UTF-8"?>
             <xsl:stylesheet version="1.0"
                  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
             <xsl:output method="text" media-type="text/calendar" />
             <xsl:template match="tour">
                   BEGIN:VCALENDAR
                   METHOD:PUBLISH
                   <xsl:for-each select="./gig">
                           BEGIN:VEVENT
                   <!-- since no datestamps in original -->
                   <!-- use same date & time            -->
                           DTSTAMP:<xsl:call-template name="getdate" />
                           DTSTART:<xsl:call-template name="getdate" />
                           SUMMARY:<xsl:value-of select="../tourname" />
                           DESCRIPTION:<xsl:value-of select="../performer" />
                           <xsl:text> </xsl:text>
                           <xsl:value-of select="./venue" />
                   </xsl:for-each>
             </xsl:template>
             <xsl:template name="getdate">
                   <xsl:value-of select="substring(date,7,4)" />
                   <xsl:value-of select="substring(date,1,2)" />
                   <xsl:value-of select="substring(date,4,2)" />
                   <xsl:text>T</xsl:text>
                   <xsl:value-of select="substring(time,1,2)" />
                   <xsl:value-of select="substring(time,4,2)" />
                   <xsl:value-of select="substring(time,7,2)" />
             </xsl:template>
             </xsl:stylesheet>






















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12.  Acknowledgments

   This document is based on previous work by Frank Dawson, Eric R.
   Plamondon, Doug Royer, and Surendra K. Reddy, whose previous XML-
   iCalendar work provided the basis for this document.  Their previous
   xCalendar work also acknowledged the contributions of Greg
   FitzPatrick, Charles Goldfarb, Paul Hoffman, Lisa Dusseault and
   Thomas Rowe.  The rdf2ical.xsl transformation created by Masahide
   Kanzaki provided inspiration and concepts for the XSL transformation
   in this document.  The primary author of this version of the document
   (T. Hare), however, assumes responsibility for all content,
   omissions, and especially errors.







































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13.  Security Considerations

   CDATA Sections - - A XML iCalendar document may contain CDATA
   sections to represent content for specific element types.  The CDATA
   section specifies arbitrary character data that is not meant to be
   interpreted.  It is not scanned	by the XML parser for markup.  While
   this memo restricts that any CDATA section MUST NOT contain markup or
   other such alternate representation for the property value, in
   general, CDATA section from a non-conformant implementation can
   contain content such as HTML markup.  HTML text can be used to invoke
   programs.	Implementors should be aware that this may leave an
   implementation open to malicious attack that might occur as a result
   of executing the markup in the CDATA section.

   PROCEDURAL ALARMS - - A XML iCalendar document can be created that
   contains a "VEVENT" and "VTODO" calendar component with "VALARM"
   calendar components.  The "VALARM" calendar component can be of type
   PROCEDURE and can have an attachment containing some sort of
   executable program.  Implementations that incorporate these types of
   alarms are subject to any virus or malicious attack that might occur
   as a result of executing the attachment.

   ATTACHMENTS - - A XML iCalendar document can include references to
   Uniform Resource Locators that can 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, since the XML objects in this memo may be exchanged via
   many possible mechanisms, the security considerations observed by
   implementations of those mechanisms should be followed for this memo.


Author's Address

   Tim Hare
   An individual
   3048 Bell Grove Dr.
   Tallahassee, FL  32308
   US

   Phone: (850)414-4209
   Email: TimHare@comcast.net









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Appendix A.  Bibliography

   [FPI] F. Dawson, "iCalendar Formal Public Identifier", Internet
   Draft,
   http://www.internic.net/internet-drafts/draft-calsch-icalfpi-00.txt,
   September 1998.

   [ISO9070] "Information Technology_SGML Support
   Facilities_Registration Procedures for Public Text Owner
   Identifiers", ISO/IEC 9070, Second Edition, International
   Organization for Standardization, April 1991.

   [RFC 2045] N. Freed, N. Borenstein, "Multipurpose Internet Mail
   Extensions 	(MIME) - Part One: Format of Internet Message Bodies",
   RFC 2045, November 1996.

   [RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate
   Requirement Levels", RFC 2119, http://www.ietf.org/rfc/rfc2119.txt,
   March 1997.

   [RFC 2445] F. Dawson and D. Stenerson, "Internet Calendaring and
   Scheduling Core Object Specification (iCalendar)", RFC 2445,
   http://www.ietf.org/rfc/rfc2445.txt, November 1998.

   [RFC 2446] F. Dawson, R. Hopson, S. Mansour, S. Silverberg
   "iCalendar Transport-	independent Interoperability Protocol", RFC
   2446, http://www.ietf.org/rfc/rfc2446.txt, November 1998

   [RFC 2447] F. Dawson, S. Mansour, S. Silverberg "iCalendar Message-
   based Interoperability Protocol", RFC 2447,
   http://www.ietf.org/rfc/rfc2447.txt, November 1998

   [CAP] G. Babics, P. Hill, S. Mansour, D. Royer "Calendar Access
   Protocol", 	Internet-Draft,
   http://www.ietf.org/internet-drafts/draft-ietf-calsch-cap-13.txt,
   January 2004

   [Previous xCalendar work] F. Dawson, S. Reddy, D. Royer, E. Plamondon
   "iCalendar DTD Document (xCal)", Internet-Draft,
   http://www.ietf.org/internet-drafts/draft-ietf-many-xcal-03.txt, July
   2002

   [XML] "Extensible Markup Language (XML)", Worldwide Web Consortium,
   http://www.w3.org/TR/REC-xml, October 2000.

   [XSL] "Extensible Stylesheet Language (XSL)", Worldwide Web
   Consortium, http://www.w3.org/TR/xsl, October 2001.




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   [XSLT] "Extensible Stylesheet Language Transformations (XSLT)",
   Worldwide Web Consortium, http://www.w3.org/TR/xslt, November 1999.

















































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Intellectual Property Statement

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   this document or the extent to which any license under such rights
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   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
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   ietf-ipr@ietf.org.


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   This document and the information contained herein are provided on an
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   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Copyright Statement

   Copyright (C) The Internet Society (2005).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.


Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.




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