Internet DRAFT - draft-royer-ical-basic
draft-royer-ical-basic
Network Working Group D. Royer
Internet-Draft IntelliCal LLC
Expires: June 27, 2006 December 24, 2005
Basic Internet Calendaring and Scheduling Core Object Specification
(iCalendar Basic)
draft-royer-ical-basic-04
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This is simplified iCalendar definistion. After having learned from
RFC-2445. This document represents the common objects needed for
basic calendaring. The VTODO, VJOURNAL, VTIMEZONE, recurrence rules
(RDATE remains), and scheduling and their associated properties have
been removed. These removals are expected to appear in new memos at
a later time and will be independent extensions of this
specification. The new EXTENSIONS property will exist to allow for
compatible sets of extensions.
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A very large part of this memo is text directly from RFC-2445. And
this memo is compatible with RFC-2445.
This memo is intented to be 100% compatible with RFC-2445. By
limiting the objects to the ones used by most vendors this version
has a better chance for interoperability and standardization.
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 definition of a common format for
openly exchanging calendaring and scheduling information across the
Internet.
This MIME media type provides a standard content type for capturing
calendar event 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,
using HTTP or some other Internet transport. In 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
and RFC-2445, RFC-2446, RFC-2447, and CAP [1] (an experimental
protocol) 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 Basic (iCal-Basic)
specification.
This memo defines the format for 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. The iCalendar
Transport-indendent Interoperability Protocol (iTIP) defined in [3]
is one such scheduling protocol.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6
2. Basic Grammar and Conventions . . . . . . . . . . . . . . . 8
2.1 Formatting Conventions . . . . . . . . . . . . . . . . . . 8
2.2 Related Memos . . . . . . . . . . . . . . . . . . . . . . 9
2.3 International Considerations . . . . . . . . . . . . . . . 9
3. Registration Information . . . . . . . . . . . . . . . . . . 10
3.1 Content Type . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 Parameters . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 Content Header Fields . . . . . . . . . . . . . . . . . . 11
3.4 Encoding Considerations . . . . . . . . . . . . . . . . . 11
3.5 Security Considerations . . . . . . . . . . . . . . . . . 12
3.6 Interoperability Considerations . . . . . . . . . . . . . 12
3.7 Applications Which Use This Media Type . . . . . . . . . . 12
3.8 Additional Information . . . . . . . . . . . . . . . . . . 13
3.9 Magic Numbers . . . . . . . . . . . . . . . . . . . . . . 13
3.10 File Extensions . . . . . . . . . . . . . . . . . . . . 13
3.11 Contact for Further Information: . . . . . . . . . . . . 13
3.12 Intended Usage . . . . . . . . . . . . . . . . . . . . . 13
4. iCalendar Object Specification . . . . . . . . . . . . . . . 14
4.1 Content Lines . . . . . . . . . . . . . . . . . . . . . . 14
4.1.1 List and Field Separators . . . . . . . . . . . . . . 16
4.1.2 Multiple Values . . . . . . . . . . . . . . . . . . . 17
4.1.3 Binary Content . . . . . . . . . . . . . . . . . . . . 17
4.1.4 Character Set . . . . . . . . . . . . . . . . . . . . 18
4.2 Property Parameters . . . . . . . . . . . . . . . . . . . 18
4.2.1 Alternate Text Representation . . . . . . . . . . . . 19
4.2.2 Common Name . . . . . . . . . . . . . . . . . . . . . 20
4.2.3 Calendar User Type . . . . . . . . . . . . . . . . . . 21
4.2.4 Delegators . . . . . . . . . . . . . . . . . . . . . . 21
4.2.5 Delegatees . . . . . . . . . . . . . . . . . . . . . . 21
4.2.6 Directory Entry Reference . . . . . . . . . . . . . . 22
4.2.7 Inline Encoding . . . . . . . . . . . . . . . . . . . 22
4.2.8 Format Type . . . . . . . . . . . . . . . . . . . . . 23
4.2.9 Free/Busy Time Type . . . . . . . . . . . . . . . . . 23
4.2.10 Language . . . . . . . . . . . . . . . . . . . . . . 24
4.2.11 Group or List Membership . . . . . . . . . . . . . . 25
4.2.12 Participation Status . . . . . . . . . . . . . . . . 25
4.2.13 Recurrence Identifier Range . . . . . . . . . . . . 26
4.2.14 Relationship Type . . . . . . . . . . . . . . . . . 26
4.2.15 Participation Role . . . . . . . . . . . . . . . . . 26
4.2.16 RSVP Expectation . . . . . . . . . . . . . . . . . . 27
4.2.17 Sent By . . . . . . . . . . . . . . . . . . . . . . 27
4.2.18 Value Data Types . . . . . . . . . . . . . . . . . . 27
4.3 Property Value Data Types . . . . . . . . . . . . . . . . 28
4.3.1 Binary . . . . . . . . . . . . . . . . . . . . . . . . 28
4.3.2 Boolean . . . . . . . . . . . . . . . . . . . . . . . 29
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4.3.3 Calendar User Address . . . . . . . . . . . . . . . . 30
4.3.4 Date . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.3.5 Date-Time . . . . . . . . . . . . . . . . . . . . . . 31
4.3.6 Duration . . . . . . . . . . . . . . . . . . . . . . . 33
4.3.7 Float . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.8 Integer . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.9 Period of Time . . . . . . . . . . . . . . . . . . . . 36
4.3.10 Recurrence Rule . . . . . . . . . . . . . . . . . . 37
4.3.11 Text . . . . . . . . . . . . . . . . . . . . . . . . 37
4.3.12 Time . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3.13 URI . . . . . . . . . . . . . . . . . . . . . . . . 40
4.3.14 UTC Offset . . . . . . . . . . . . . . . . . . . . . 41
4.4 iCalendar Object . . . . . . . . . . . . . . . . . . . . . 41
4.5 Property . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.6 Calendar Components . . . . . . . . . . . . . . . . . . . 42
4.6.1 Event Component . . . . . . . . . . . . . . . . . . . 43
4.6.2 To-do Component . . . . . . . . . . . . . . . . . . . 46
4.6.3 Journal Component . . . . . . . . . . . . . . . . . . 46
4.6.4 Free/Busy Component . . . . . . . . . . . . . . . . . 46
4.6.5 Time Zone Component . . . . . . . . . . . . . . . . . 49
4.6.6 Alarm Component . . . . . . . . . . . . . . . . . . . 49
4.7 Calendar Properties . . . . . . . . . . . . . . . . . . . 54
4.7.1 Calendar Scale . . . . . . . . . . . . . . . . . . . . 55
4.7.2 Method . . . . . . . . . . . . . . . . . . . . . . . . 55
4.7.3 Product Identifier . . . . . . . . . . . . . . . . . . 56
4.7.4 Version . . . . . . . . . . . . . . . . . . . . . . . 57
4.8 Component Properties . . . . . . . . . . . . . . . . . . . 58
4.8.1 New Properties . . . . . . . . . . . . . . . . . . . . 58
4.8.2 Descriptive Component Properties . . . . . . . . . . . 59
4.8.3 Date and Time Component Properties . . . . . . . . . . 70
4.8.4 Time Zone Component Properties . . . . . . . . . . . . 76
4.8.5 Time Zone Name . . . . . . . . . . . . . . . . . . . . 76
4.8.6 Time Zone Offset From . . . . . . . . . . . . . . . . 76
4.8.7 Time Zone Offset To . . . . . . . . . . . . . . . . . 76
4.8.8 Time Zone URL . . . . . . . . . . . . . . . . . . . . 76
4.9 Relationship Component Properties . . . . . . . . . . . . 76
4.9.1 Attendee . . . . . . . . . . . . . . . . . . . . . . . 76
4.9.2 Contact . . . . . . . . . . . . . . . . . . . . . . . 79
4.9.3 Organizer . . . . . . . . . . . . . . . . . . . . . . 80
4.9.4 Recurrence ID . . . . . . . . . . . . . . . . . . . . 82
4.9.5 Related To . . . . . . . . . . . . . . . . . . . . . . 82
4.9.6 Uniform Resource Locator . . . . . . . . . . . . . . . 82
4.9.7 Unique Identifier . . . . . . . . . . . . . . . . . . 83
4.10 Recurrence Component Properties . . . . . . . . . . . . 84
4.10.1 Exception Date/Times . . . . . . . . . . . . . . . . 84
4.10.2 Exception Rule . . . . . . . . . . . . . . . . . . . 84
4.10.3 Recurrence Date/Times . . . . . . . . . . . . . . . 84
4.10.4 Recurrence Rule . . . . . . . . . . . . . . . . . . 86
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4.11 Alarm Component Properties . . . . . . . . . . . . . . . 86
4.11.1 Action . . . . . . . . . . . . . . . . . . . . . . . 86
4.11.2 Repeat Count . . . . . . . . . . . . . . . . . . . . 87
4.11.3 Trigger . . . . . . . . . . . . . . . . . . . . . . 88
4.12 Change Management Component Properties . . . . . . . . . 90
4.12.1 Date/Time Created . . . . . . . . . . . . . . . . . 90
4.12.2 Date/Time Stamp . . . . . . . . . . . . . . . . . . 90
4.12.3 Last Modified . . . . . . . . . . . . . . . . . . . 91
4.12.4 Sequence Number . . . . . . . . . . . . . . . . . . 92
4.13 Miscellaneous Component Properties . . . . . . . . . . . 93
4.13.1 Non-standard Properties . . . . . . . . . . . . . . 93
4.13.2 Request Status . . . . . . . . . . . . . . . . . . . 94
5. iCalendar Object Examples . . . . . . . . . . . . . . . . . 97
6. Recommended Practices . . . . . . . . . . . . . . . . . . . 100
7. Registration of Content Type Elements . . . . . . . . . . . 102
7.1 Registration of New and Modified iCalendar Object
Methods . . . . . . . . . . . . . . . . . . . . . . . . . 102
7.2 Registration of New Properties . . . . . . . . . . . . . . 102
7.2.1 Define the property . . . . . . . . . . . . . . . . . 102
7.2.2 Post the Property definition . . . . . . . . . . . . . 103
7.2.3 Allow a comment period . . . . . . . . . . . . . . . . 103
7.2.4 Submit the property for approval . . . . . . . . . . . 103
7.3 Property Change Control . . . . . . . . . . . . . . . . . 104
8. References (BOILERPLATE) . . . . . . . . . . . . . . . . . . 105
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 106
10. Authors' and Chairs' Addresses (BOILERPLATE) . . . . . . . . 107
11. Full Copyright Statement (BOILERPLATE) . . . . . . . . . . . 108
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 108
Author's Address . . . . . . . . . . . . . . . . . . . . . . 109
Intellectual Property and Copyright Statements . . . . . . . 110
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1. Introduction
While implementing iCalendar applications much has been learned.
Among those lessions is the need to make a simpler version of
iCalendar that includes the common features used by almost all
vendors. This memo describes a 'Basic' version of iCalendar that
does not include recurrence rules, to-do's, journals, or timezones.
These removals may be added in separate memos at a later time. These
simplifications are seen as a way for more vendors to produce objects
that are compatible with each other and without having to support all
of the features possible in RFC-2445. A new property called
EXTENSIONS allows for those conforming to this specification to
detect any optional features while existing RFC-2445 implementations
should already ignore the unknown property. A few properties have
been tagged as no longer needed, these are marked as 'deprecated' in
the sections that follow (GEO for example). And other properties and
components are tagged as not in iCal-Basic, these may be reintroduced
in future memos (RRULE for example).
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 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 purpose of an iCalendar objects is for exchanging calendar
information between applications. iCalendar objects were not designed
to be a calendar store file storage format. This specification makes
no assumptions or recommendations about how an application stores
iCalendar objects it generates or receives for use in its own
calendar store. iCalendar objects simply exist to transfer
information about a calendar entry from one application to another.
When an iCalendar object is stored outside of the applications
calendar store, then it should be saved using the ".ics" file
extension or transfered in a "text/calendar" MIME object. The MIME
transfer of an iCalendar object is described in iTIP and CAP. The
email transfer of an iCalendar object is described in iMIP and iTIP.
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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 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 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. 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
[3].
The memo also includes a formal grammar for the content type based on
the Internet ABNF defined in [13]. 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.
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2. Basic Grammar and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY" and
"OPTIONAL" in this document are to be interoperated as described in
[12].
This memo makes use of both a descriptive prose and a more formal
notation for defining the calendaring and scheduling format.
The notation used in this memo is the ABNF notation of [13]. 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. The
information is not essential to the building of an implementation
conformant with this memo. The information is provided to
highlight a particular feature or characteristic of the memo.
The format for the iCalendar object is based on the syntax of the
[15] content type. While the iCalendar object is not a profile of
the [15] content type, it does reuse a number of the elements from
the [15] specification.
2.1 Formatting Conventions
The mechanisms defined in this memo are defined in prose. Many of
the terms used to describe these have common usage that is different
than the standards usage of this memo. In order to reference within
this memo elements of the calendaring and scheduling model, core
object (this memo) or interoperability protocol [3] some formatting
conventions have been used. Calendaring and scheduling roles 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 [3].
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
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calendar component. Scheduling methods defined by [3] 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 lowercase, quoted-strings
of text, 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 "CANCELED"
value can be used with the "STATUS" property.
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-BASIC], specifies a core
specification of objects, data types, properties and property
parameters.
[3] - specifies an interoperability protocol for scheduling between
different implementations;
[2] specifies an Internet email binding for [3].
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.
2.3 International Considerations
In the rest of this document, descriptions of characters are of the
form "character name (codepoint)", where "codepoint" is from the US-
ASCII character set. The "character name" is the authoritative
description; (codepoint) is a reference to that character in US-ASCII
or US-ASCII compatible sets (for example the ISO-8859-x family, UTF-
8, ISO-2022-xx, KOI8-R). If a non-US-ASCII compatible character set
is used, appropriate code-point from that character set MUST be
chosen instead. Use of non-US-ASCII-compatible character sets is NOT
recommended.
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3. 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.
3.1 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
3.2 Parameters
Required parameters: none
Optional parameters: charset, method, component and optinfo
The "charset" parameter is defined in [10] for other body parts. It
is used to identify the default character set used within the body
part.
The "method" parameter is used to convey the iCalendar object method
or transaction semantics for the calendaring and scheduling
information. It also is an identifier for the restricted set of
properties and values that the iCalendar object consists of. The
parameter is to be used as a guide for applications interpreting the
information contained within the body part. It 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 can contain any set of properties
permitted by the Calendaring and Scheduling Core Object
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 / "-")
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; IANA registered iCalendar object method
The "component" parameter conveys the type of iCalendar calendar
component within the body part. If the iCalendar object contains
more than one calendar component type, then multiple component
parameters MUST be specified.
The value for the "component" parameter is defined as follows:
component = "VFREEBUSY"
/ x-name / iana-token)
The "optinfo" parameter conveys optional information about the
iCalendar object within the body part. This parameter can only
specify semantics already specified by the iCalendar object and that
can be otherwise determined by parsing the body part. In addition,
the optional information specified by this parameter MUST be
consistent with that information specified by the iCalendar object.
For example, it can be used to convey the "Attendee" response status
to a meeting request. The parameter value consists of a string
value.
The parameter can be specified multiple times.
This parameter MAY only specify semantics already specified by the
iCalendar object and that can be otherwise determined by parsing the
body part.
The value for the "optinfo" parameter is defined as follows:
optinfo = infovalue / qinfovalue
infovalue = iana-token / x-name
qinfovalue = DQUOTE (infovalue) DQUOTE
3.3 Content Header Fields
Optional content header fields: Any header fields defined by [RFC
2045].
3.4 Encoding Considerations
This MIME content type can contain 8bit characters, so the use of
quoted-printable or BASE64 MIME content-transfer-encodings might be
necessary when iCalendar objects are transferred across protocols
restricted to the 7bit repertoire. Note that a text valued property
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in the content entity can also have content encoding of special
characters using a BACKSLASH character (US-ASCII decimal 92)
escapement technique. This means that content values can end up
encoded twice.
3.5 Security Considerations
SPOOFING - - In this memo, the "Organizer" is the only person
authorized to make changes to an existing "VEVENT" calendar component
and redistribute the updates to the "Attendees". An iCalendar object
that maliciously changes or cancels an existing "VEVENT" or
"VFREEBUSY" calendar component might 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"
calendar component is the only other person authorized to update any
parameter associated with their "ATTENDEE" property and send it to
the "Organizer". An iCalendar object that maliciously changes the
"ATTENDEE" parameters can 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" 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 - - An iCalendar object 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, the security considerations observed by implementations of
electronic mail systems should be followed for this memo.
3.6 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 [18] industry
specification.
3.7 Applications Which Use This Media Type
This content-type is designed for widespread use by Internet
calendaring and scheduling applications. In addition, applications
in the workflow and document management area might find this content-
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type applicable. The [3] and [2] Internet protocols directly use
this content-type also. Future work on an Internet calendar access
protocol will utilize this content-type too.
3.8 Additional Information
This memo defines this content-type.
3.9 Magic Numbers
None.
3.10 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. This file
extension exists to be used by applications and operating systems to
uniqely identify iCalendar objects that are placed into a file or
sent in email. This specification makes no assumptions or
recommendations about how an application stores iCalendar objects it
generates or receives for use in its own calendar store.
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 "iFBf" 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.
3.11 Contact for Further Information:
Doug Royer
267 Kentlands Blvd., #3041
Gaithersburg, MD 20878
208-612-4639
Doug@Royer.com
3.12 Intended Usage
COMMON
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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 can 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 Lines
The iCalendar object is organized into individual lines of text,
called content lines. Content lines are delimited by a line break,
which is a CRLF sequence (US-ASCII decimal 13, followed by US-ASCII
decimal 10).
Lines of text SHOULD NOT be longer than 75 octets, excluding the line
break. Long content lines SHOULD be split into a multiple line
representations using a line "folding" technique. That is, a long
line can be split between any two characters by inserting a CRLF
immediately followed by a single linear white space character (i.e.,
SPACE, US-ASCII decimal 32 or HTAB, US-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 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.
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 octets SHOULD be
folded according to the folding procedure described above.
The content information associated with an iCalendar object is
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formatted using a syntax similar to that defined by [15]. That is,
the content information consists of CRLF-separated content lines.
The following notation defines the lines of content in an iCalendar
object:
contentline = name *(";" param ) ":" value CRLF
; 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 octets SHOULD be folded according to
; the folding procedure described above.
name = x-name / iana-token
iana-token = 1*(ALPHA / DIGIT / "-")
; iCalendar identifier registered with IANA
x-name = "X-" [vendorid "-"] 1*(ALPHA / DIGIT / "-")
; Reservered for experimental use. Not intended for use in
; released products.
vendorid = 3*(ALPHA / DIGIT) ;Vendor identification
param = param-name "=" param-value
*("," param-value)
; Each property defines the specific ABNF for the parameters
; allowed on the property. Refer to specific properties for
; precise parameter ABNF.
param-name = iana-token / x-token
param-value = paramtext / quoted-string
paramtext = *SAFE-CHAR
value = *VALUE-CHAR
quoted-string = DQUOTE *QSAFE-CHAR DQUOTE
NON-US-ASCII = %x80-F8
; Use restricted by charset parameter
; on outer MIME object (UTF-8 preferred)
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QSAFE-CHAR = WSP / %x21 / %x23-7E / NON-US-ASCII
; Any character except CTLs and DQUOTE
SAFE-CHAR = WSP / %x21 / %x23-2B / %x2D-39 / %x3C-7E
/ NON-US-ASCII
; Any character except CTLs, DQUOTE, ";", ":", ","
VALUE-CHAR = WSP / %x21-7E / NON-US-ASCII
; Any textual character
CR = %x0D
; carriage return
LF = %x0A
; line feed
CRLF = CR LF
; Internet standard newline
CTL = %x00-08 / %x0A-1F / %x7F
; Controls
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
DIGIT = %x30-39
; 0-9
DQUOTE = %x22
; Quotation Mark
WSP = SPACE / HTAB
SPACE = %x20
HTAB = %x09
The property value 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.
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.
4.1.1 List and Field Separators
Some properties and parameters allow a list of values. Values in a
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list of values MUST be separated by a COMMA character (US-ASCII
decimal 44). There is no significance to the order of values in a
list. For those parameter values (such as those that specify URI
values) that are specified in quoted-strings, the individual quoted-
strings are separated by a COMMA character (US-ASCII decimal 44).
Some property values are defined in terms of multiple parts. These
structured property values MUST have their value parts separated by a
SEMICOLON character (US-ASCII decimal 59).
Some properties allow a list of parameters. Each property parameter
in a list of property parameters MUST be separated by a SEMICOLON
character (US-ASCII decimal 59).
Property parameters with values containing a COLON, a SEMICOLON or a
COMMA character MUST be placed in quoted text.
For example, in the following properties a SEMICOLON is used to
separate property parameters from each other, and a COMMA is used to
separate property values in a value list.
ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:MAILTO:
jsmith@host.com
RDATE;VALUE=DATE:19970304,19970504,19970704,19970904
4.1.2 Multiple Values
Some properties defined in the iCalendar object can have multiple
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 (US-ASCII decimal 44). Individual
property definitions should be consulted for determining whether a
specific property allows multiple values and in which of these two
forms.
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
applications where this is not feasible, binary content information
can be included within an iCalendar object, but only after first
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encoding it into text using the "BASE64" encoding method defined in
[9]. Inline binary contact SHOULD only be used in applications whose
special circumstances demand that an iCalendar object be expressed as
a single entity. 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;FMTTYPE=image/basic;ENCODING=BASE64;VALUE=BINARY:
MIICajCCAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQAwdzELMAkGA1U
EBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb25zIE
<...remainder of "BASE64" encoded binary data...>
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 as defined in [14].
The "charset" Content-Type parameter can be used in MIME transports
to specify any other IANA registered character set.
4.2 Property Parameters
A property can have attributes associated with it. These "property
parameters" contain meta-information about the property or the
property value. Property parameters are provided to specify such
information as the location of an alternate text representation for a
property value, the language of a text property value, the data type
of the property value and other attributes.
Property parameter values that contain the COLON (US-ASCII decimal
58), SEMICOLON (US-ASCII decimal 59) or COMMA (US-ASCII decimal 44)
character separators MUST be specified as quoted-string text values.
Property parameter values MUST NOT contain the DOUBLE-QUOTE (US-ASCII
decimal 22) character. The DOUBLE-QUOTE (US-ASCII decimal 22)
character is used as a delimiter for parameter values that contain
restricted characters or URI text. For example:
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DESCRIPTION;ALTREP="http://www.wiz.org":The Fall'98 Wild Wizards
Conference - - Las Vegas, NV, USA
Property parameter values that are not in quoted strings are case
insensitive.
The general property parameters defined by this memo are defined by
the following notation:
parameter = altrepparam ; Alternate text representation
/ cnparam ; Common name
/ cutypeparam ; Calendar user type
/ delfromparam ; Delegator
/ deltoparam ; Delegatee
/ dirparam ; Directory entry
/ encodingparam ; Inline encoding
/ fmttypeparam ; Format type
/ fbtypeparam ; Free/busy time type
/ languageparam ; Language for text
/ memberparam ; Group or list membership
/ partstatparam ; Participation status
/ rangeparam ; Recurrence identifier range
/ trigrelparam ; Alarm trigger relationship
/ reltypeparam ; Relationship type
/ roleparam ; Participation role
/ rsvpparam ; RSVP expectation
/ sentbyparam ; Sent by
/ valuetypeparam ; Property value data type
/ ianaparam
; Some other IANA registered iCalendar parameter.
/ xparam
; A non-standard, experimental parameter.
ianaparam = iana-token "=" param-value *("," param-value)
xparam =x-name "=" param-value *("," param-value)
4.2.1 Alternate Text Representation
Parameter Name: ALTREP
Purpose: To specify an alternate text representation for the property
value.
Format Definition: The property parameter is defined by the following
notation:
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altrepparam = "ALTREP" "=" DQUOTE uri DQUOTE
Description: The parameter specifies a URI that points to an
alternate representation for a textual property value. A property
specifying this parameter MUST also include a value that reflects the
default representation of the text value. The individual URI
parameter values MUST each be specified in a quoted-string.
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.
Content-Type:text/html
Content-Id:<part3.msg.970415T083000@host.com>
<html><body>
<p><b>Project XYZ Review Meeting</b> will include the following
agenda items:<ol><li>Market
Overview</li><li>Finances</li><li>Project Management</li></ol></p>
</body></html>
4.2.2 Common Name
Parameter Name: CN
Purpose: To specify the common name to be associated with the
calendar user specified by the property.
Format Definition: The property parameter is defined by the following
notation:
cnparam = "CN" "=" param-value
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter specifies the common name to
be associated with the calendar user specified by the property. The
parameter value is text. The parameter value can be used for display
text to be associated with the calendar address specified by the
property.
Example:
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ORGANIZER;CN="John Smith":MAILTO:jsmith@host.com
4.2.3 Calendar User Type
Parameter Name: CUTYPE
Purpose: To specify the type of calendar user specified by the
property.
Format Definition: The property parameter is defined by the following
notation:
cutypeparam = "CUTYPE" "="
("INDIVIDUAL" ; An individual
/ "GROUP" ; A group of individuals
/ "RESOURCE" ; A physical resource
/ "ROOM" ; A room resource
/ "UNKNOWN" ; Otherwise not known
/ x-name ; Experimental type
/ iana-token) ; Other IANA registered
; type
; Default is INDIVIDUAL
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter identifies the type of
calendar user specified by the property. If not specified on a
property that allows this parameter, the default is INDIVIDUAL.
Example:
ATTENDEE;CUTYPE=GROUP:MAILTO:ietf-calsch@imc.org
4.2.4 Delegators
Parameter Name: DELEGATED-FROM
DELEGATED-FROM is not in iCal-Basic.
4.2.5 Delegatees
Parameter Name: DELEGATED-TO
DELEGATED-FROM is not in iCal-Basic.
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4.2.6 Directory Entry Reference
Parameter Name: DIR
Purpose: To specify reference to a directory entry associated with
the calendar user specified by the property.
Format Definition: The property parameter is defined by the following
notation:
dirparam = "DIR" "=" DQUOTE uri DQUOTE
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter specifies a reference to the
directory entry associated with the calendar user specified by the
property. The parameter value is a URI. The individual URI
parameter values MUST each be specified in a quoted-string.
Example:
ORGANIZER;DIR="ldap://host.com:6666/o=eDABC%20Industries,c=3DUS??
(cn=3DBJim%20Dolittle)":MAILTO:jimdo@host1.com
4.2.7 Inline Encoding
Parameter Name: ENCODING
Purpose: To specify an alternate inline encoding for the property
value.
Format Definition: The property parameter is defined by the following
notation:
encodingparam = "ENCODING" "="
("8BIT"
; "8bit" text encoding is defined in [RFC.2045]
/ "BASE64"
; "BASE64" binary encoding format is defined in [RFC.2045]
/ iana-token
; Some other IANA registered iCalendar encoding type
/ x-name)
; A non-standard, experimental encoding type
Description: The property parameter identifies the inline encoding
used in a property value. The default encoding is "8BIT",
corresponding to a property value consisting of text. The "BASE64"
encoding type corresponds to a property value encoded using the
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"BASE64" encoding defined in [9].
If the value type parameter is ";VALUE=BINARY", then the inline
encoding parameter MUST be specified with the value
";ENCODING=BASE64".
Example:
ATTACH;FMTYPE=IMAGE/JPEG;ENCODING=BASE64;VALUE=BINARY:MIICajC
CAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDA
qBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRw
<...remainder of "BASE64" encoded binary data...>
4.2.8 Format Type
Parameter Name: FMTTYPE
Purpose: To specify the content type of a referenced object.
Format Definition: The property parameter is defined by the following
notation:
fmttypeparam = "FMTTYPE" "=" iana-token
; A IANA registered content type
/ x-name
; A non-standard content type
Description: This parameter can be specified on properties that are
used to reference an object. The parameter specifies the content
type of the referenced object. For example, on the "ATTACH"
property, a FTP type URI value does not, by itself, necessarily
convey the type of content associated with the resource. The
parameter value MUST be the TEXT for either an IANA registered
content type or a non-standard content type.
Example:
ATTACH;FMTTYPE=application/binary:ftp://domain.com/pub/docs/
agenda.doc
4.2.9 Free/Busy Time Type
Parameter Name: FBTYPE
Purpose: To specify the free or busy time type.
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Format Definition: The property parameter is defined by the following
notation:
fbtypeparam = "FBTYPE" "=" ("FREE" / "BUSY"
/ "BUSY-UNAVAILABLE" / "BUSY-TENTATIVE"
/ x-name
; Some experimental iCalendar data type.
/ iana-token)
; Some other IANA registered iCalendar data type.
Description: The parameter specifies the free or busy time type. The
value FREE indicates that the time interval is free for scheduling.
The value BUSY indicates that the time interval is busy because one
or more events have been scheduled for that interval. The value
BUSY-UNAVAILABLE indicates that the time interval is busy and that
the interval can not be scheduled. The value BUSY-TENTATIVE
indicates that the time interval is busy because one or more events
have been tentatively scheduled for that interval. If not specified
on a property that allows this parameter, the default is BUSY.
Example: The following is an example of this parameter on a FREEBUSY
property.
FREEBUSY;FBTYPE=BUSY:19980415T133000Z/19980415T170000Z
4.2.10 Language
Parameter Name: LANGUAGE
Purpose: To specify the language for text values in a property or
property parameter.
Format Definition: The property parameter is defined by the following
notation:
languageparam = "LANGUAGE" "=" language
language = <Text identifying a language, as defined in [RFC.1766]
Description: This parameter can be specified on properties with a
text value type. The parameter identifies the language of the text
in the property or property parameter value. The value of the
"language" property parameter is that defined in [8].
For transport in a MIME entity, the Content-Language header field can
be used to set the default language for the entire body part.
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Otherwise, no default language is assumed.
Example:
SUMMARY;LANGUAGE=us-EN:Company Holiday Party
LOCATION;LANGUAGE=en:Germany
LOCATION;LANGUAGE=no:Tyskland
The following example makes use of the Quoted-Printable encoding in
order to represent non-ASCII characters.
LOCATION;LANGUAGE=da:K=F8benhavn
LOCATION;LANGUAGE=en:Copenhagen
4.2.11 Group or List Membership
Parameter Name: MEMBER
Purpose: To specify the group or list membership of the calendar user
specified by the property.
Format Definition: The property parameter is defined by the following
notation:
memberparam = "MEMBER" "=" DQUOTE cal-address DQUOTE
*("," DQUOTE cal-address DQUOTE)
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter identifies the groups or list
membership for the calendar user specified by the property. The
parameter value either a single calendar address in a quoted-string
or a COMMA character (US-ASCII decimal 44) list of calendar
addresses, each in a quoted-string. The individual calendar address
parameter values MUST each be specified in a quoted-string.
Example:
ATTENDEE;MEMBER="MAILTO:ietf-calsch@imc.org":MAILTO:jsmith@host.com
ATTENDEE;MEMBER="MAILTO:projectA@host.com","MAILTO:projectB@host.
com":MAILTO:janedoe@host.com
4.2.12 Participation Status
Parameter Name: PARTSTAT
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Purpose: To specify the participation status for the calendar user
specified by the property.
Format Definition: The property parameter is defined by the following
notation:
; These are the participation statuses for a "VEVENT". Default is
; NEEDS-ACTION
partstatparam = "PARTSTAT" "="
("NEEDS-ACTION" ; Event needs action
/ "ACCEPTED" ; Event accepted
/ "DECLINED" ; Event declined
/ "TENTATIVE" ; Event tentatively
; accepted
/ "DELEGATED" ; Event delegated
/ x-name ; Experimental status
/ iana-token) ; Other IANA registered
; status
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter identifies the participation
status for the calendar user specified by the property value. The
parameter values differ depending on whether they are associated with
a group scheduled "VEVENT". The values MUST match one of the values
allowed for the given calendar component. If not specified on a
property that allows this parameter, the default value is NEEDS-
ACTION.
Example:
ATTENDEE;PARTSTAT=DECLINED:MAILTO:jsmith@host.com
4.2.13 Recurrence Identifier Range
Not in iCal-Basic.
4.2.14 Relationship Type
Parameter Name: RELTYPE
Deprecated along with the RELATED-TO property.
4.2.15 Participation Role
Parameter Name: ROLE
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Purpose: To specify the participation role for the calendar user
specified by the property.
Format Definition: The property parameter is defined by the following
notation:
roleparam = "ROLE" "="
("CHAIR" ; Indicates chair of the
; calendar entity
/ "REQ-PARTICIPANT" ; Indicates a participant whose
; participation is required
/ "OPT-PARTICIPANT" ; Indicates a participant whose
; participation is optional
/ "NON-PARTICIPANT" ; Indicates a participant who is
; copied for information
; purposes only
/ x-name ; Experimental role
/ iana-token) ; Other IANA role
; Default is REQ-PARTICIPANT
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter specifies the participation
role for the calendar user specified by the property in the group
schedule calendar component. If not specified on a property that
allows this parameter, the default value is REQ-PARTICIPANT.
Example:
ATTENDEE;ROLE=CHAIR:MAILTO:mrbig@host.com
4.2.16 RSVP Expectation
Parameter Name: RSVP
RSVP is not in iCal-Basic.
4.2.17 Sent By
Parameter Name: SENT-BY
SENT-BY is not in iCal-Basic.
4.2.18 Value Data Types
Parameter Name: VALUE
Purpose: To explicitly specify the data type format for a property
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value.
Format Definition: The "VALUE" property parameter is defined by the
following notation:
valuetypeparam = "VALUE" "=" valuetype
valuetype = ("BINARY"
/ "BOOLEAN"
/ "CAL-ADDRESS"
/ "DATE"
/ "DATE-TIME"
/ "DURATION"
/ "INTEGER"
/ "PERIOD"
/ "TEXT"
/ "TIME"
/ "URI"
/ x-name
; Some experimental iCalendar data type.
/ iana-token)
; Some other IANA registered iCalendar data type.
Description: The parameter specifies the data type and format of the
property value. The property values MUST be of a single value type.
For example, a "RDATE" property cannot have a combination of DATE-
TIME and TIME value types.
If the property's value is the default value type, then this
parameter need not be specified. However, if the property's default
value type is overridden by some other allowable value type, then
this parameter MUST be specified.
4.3 Property Value Data Types
The properties in an iCalendar object are strongly typed. The
definition of each property restricts the value to be one of the
value data types, or simply value types, defined in this section.
The value type for a property will either be specified implicitly as
the default value type or will be explicitly specified with the
"VALUE" parameter. If the value type of a property is one of the
alternate valid types, then it MUST be explicitly specified with the
"VALUE" parameter.
4.3.1 Binary
Value Name: BINARY
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Purpose: This value type is used to identify properties that contain
a character encoding of inline binary data. For example, an inline
attachment of an object code might be included in an iCalendar
object.
Formal Definition: The value type is defined by the following
notation:
binary = *(4b-char) [b-end]
; A "BASE64" encoded character string, as defined by [RFC.2045].
b-end = (2b-char "==") / (3b-char "=")
b-char = ALPHA / DIGIT / "+" / "/"
Description: Property values with this value type MUST also include
the inline encoding parameter sequence of ";ENCODING=BASE64". That
is, all inline binary data MUST first be character encoded using the
"BASE64" encoding method defined in [9]. 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 "BASE64" encoded
binary value data.
ATTACH;VALUE=BINARY;ENCODING=BASE64:MIICajCCAdOgAwIBAgICBEUwDQY
JKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlI
ENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZv
<...remainder of "BASE64" encoded binary data...>
4.3.2 Boolean
Value Name: BOOLEAN
Purpose: This value type is used to identify properties that contain
either a "TRUE" or "FALSE" Boolean value.
Formal Definition: The value type is defined by the following
notation:
boolean = "TRUE" / "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: The following is an example of a hypothetical property that
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has a BOOLEAN value type:
GIBBERISH:TRUE
4.3.3 Calendar User Address
Value Name: CAL-ADDRESS
Purpose: This value type is used to identify properties that contain
a calendar user address.
Formal Definition: The value type is as defined by the following
notation:
cal-address = uri
Description: The value is a URI as defined by [7] 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 [7]. No additional content value encoding (i.e.,
BACKSLASH character encoding) is defined for this value type.
Example:
ATTENDEE:MAILTO:jane_doe@host.com
4.3.4 Date
Value Name: DATE
Purpose: This value type is used to identify values that contain a
calendar date.
Formal Definition: The value type is defined by the following
notation:
date = 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 "date" values are
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specified as a COMMA character (US-ASCII decimal 44) separated list
of values. The format for the value type is expressed as the [ISO
8601] complete representation, basic format for a calendar date. The
textual format specifies a four-digit year, two-digit month, and two-
digit day of the month. There are no separator characters between
the year, month and day component text.
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
Example: The following represents July 14, 1997:
19970714
4.3.5 Date-Time
Value Name: DATE-TIME
Purpose: This value type is used to identify values that specify a
precise calendar date and time of day.
Formal Definition: The value type is defined by the following
notation:
date-time = date "T" time ;As specified in the date and time
;value definitions
Description: If the property permits, multiple "date-time" values are
specified as a COMMA character (US-ASCII decimal 44) separated list
of values. No additional content value encoding (i.e., BACKSLASH
character encoding) is defined for this value type.
The "DATE-TIME" data type is used to identify values that contain a
precise calendar date and time of day. The format is based on the
[4] complete representation, basic format for a calendar date and
time of day. The text format is a concatenation of the "date",
followed by the LATIN CAPITAL LETTER T character (US-ASCII decimal
84) time designator, followed by the "time" format.
The "DATE-TIME" data type expresses time values in three forms:
The form of date and time with UTC offset MUST NOT be used. For
example, the following is not valid for a date-time value:
DTSTART:19980119T230000-0800 ;Invalid time format
FORM #1: DATE WITH LOCAL TIME
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The date with local time form is simply a 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 this type are said to be "floating" and are not
bound to any time zone in particular. They are used to represent the
same hour, minute, and second value regardless of which time zone is
currently being observed. For example, an event can be defined that
indicates that an individual will be busy from 11:00 AM to 1:00 PM
every day, no matter which time zone the person is in. In these
cases, a local time can be specified. The recipient of an iCalendar
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 time zone the ATTENDEE is in at any given moment.
This means that two ATTENDEEs, in different time zones, receiving the
same event definition as a floating time, may be participating in the
event at different actual times. Floating time SHOULD only be used
where that is the reasonable behavior.
In most cases, a fixed time is desired. To properly communicate a
fixed time in a property value, UTC time must be specified. Time
zones are not in iCal-Basic and may be added in a future extension.
FORM #2: DATE WITH UTC TIME
The date with UTC time, or absolute time, is identified by a LATIN
CAPITAL LETTER Z suffix character (US-ASCII decimal 90), the UTC
designator, appended to the time value. For example, the following
represents January 19, 1998, at 0700 UTC:
DTSTART:19980119T070000Z
FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE
Are not supported or needed in iCal-Basic implementations. Time zone
information is needed only when including recurring rules (the RFC-
2445 RRULE and EXRULE) and they may be added at a later time.
Example: The following represents July 14, 1997, at 1:30 PM in New
York City in each of the two time formats, using the "DTSTART"
property.
DTSTART:19970714T133000 ;Local time
DTSTART:19970714T173000Z ;UTC time
A time value MUST ONLY specify 60 seconds when specifying the
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periodic "leap second" in the time value. For example:
COMPLETED:19970630T235960Z
4.3.6 Duration
Value Name: DURATION
Purpose: This value type is used to identify properties that contain
a duration of time.
Formal Definition: The value type is defined by the following
notation:
dur-value = (["+"] / "-") "P" (dur-date / dur-time / dur-week)
dur-date = dur-day [dur-time]
dur-time = "T" (dur-of-time)
dur-week = 1*DIGIT "W"
dur-of-time = 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 are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. The format is expressed as the [4] basic format for the
duration of time. The format can represent durations in terms of
weeks, days, hours, minutes, and seconds.
No additional content value encoding (i.e., BACKSLASH character
encoding) are defined for this value type.
One week (1W) is defined to mean seven days (7D).
One day (1D) is defined to mean add one to the date part. If is what
you really need is 24 hours, use "24H" and not "1D". This matters
when one or more instances have their start or end time across a time
zone change within one single time zone (Wall clock has 1 hour added
to it or subtracted from it when the time zone changes). And the
time part is not effected. So "1D" added to a date part when the
time zone changes could mean that the appointment is 23 hours long or
25 hours long, depending on how the time zone changes. In all cases,
add to the 'date' part and not to the 'time' part for 'dur-day'
duration parts.
One hour (1H) is defined to mean 60 minutes (60M).
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One minute (1M) is defined to mean 60 seconds (60S). If an
implementation cares about that leap second, then send the time in
seconds (Example: Send "61S" or "1M1S" and not "1M").
The 'dur-hour', 'dur-minute', 'dur-minute', and 'dur-day' property
value parts do not need to be normalized. Example: One
implementation may send "3600S" and another "1H" and they are
equivelent. The value part "1D" is not always equivelent to "24H".
The order of addition is 'W', 'D', 'H', 'M', then 'S'. In that
order.
Note that some existing calendaring implementations include the 'dur-
time' parts that are zero and others do not. For example one
implementation might send a value of "+PT30S" and another
implementation might send "+PT0H0M30S". The ABNF above shows that
the abbreivated format is deprecated. The new 'dur-of-time' always
includes the 'H', 'M', and 'S' parts even when they are zero. This
is done so that there is exactly one way to send the time part of a
duration.
Example: A duration of 15 days, 5 hours and 20 seconds would be:
P15DT5H0M20S
A duration of 7 weeks would be:
P7W
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Given
DTSTART:20050401T235959
DURATATION:+P1DT0H0M1S
Add 1D gives:
End time of: 20050402T235959
Then add 1S should result in.
End time of: 20050403T000000
Given:
DTSTART:20050401T235959
DURATION:+P1W
Add 1W gives:
End time of: 20040408T235959
4.3.7 Float
Value Name: FLOAT
Deprecated. Was only used with GEO which is deprecated.
4.3.8 Integer
Value Name:INTEGER
Purpose: This value type is used to identify properties that contain
a signed integer value.
Formal Definition: The value type is defined by the following
notation:
integer = (["+"] / "-") 1*DIGIT
Description: If the property permits, multiple "integer" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. The valid range for "integer" is -2147483648 to
2147483647. If the sign is not specified, then the value is assumed
to be positive.
No additional content value encoding (i.e., BACKSLASH character
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encoding) is defined for this value type.
Example:
1234567890
-1234567890
+1234567890
432109876
4.3.9 Period of Time
Value Name: PERIOD
Purpose: This value type is used to identify values that contain a
precise period of time.
Formal Definition: The data type is defined by the following
notation:
period = 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 start MUST be before the
; end.
period-start = date-time "/" dur-value
; [ISO.8601] complete representation basic format for a period of
; time consisting of a start and positive duration of time.
Description: If the property permits, multiple "period" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. There are two forms of a period of time. First, a period
of time is identified by its start and its end. This format is
expressed as the [4] complete representation, basic format for "DATE-
TIME" start of the period, followed by a SOLIDUS character (US-ASCII
decimal 47), followed by the "DATE-TIME" of the end of the period.
The start of the period MUST be before the end of the period.
Second, a period of time can also be defined by a start and a
positive duration of time. The format is expressed as the [4]
complete representation, basic format for the "DATE-TIME" start of
the period, followed by a SOLIDUS character (US-ASCII decimal 47),
followed by the [4] basic format for "DURATION" of the 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:
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19970101T180000Z/19970102T070000Z
The period start at 18:00:00 on January 1, 1997 and lasting 5 hours
and 30 minutes would be:
19970101T180000Z/PT5H30M
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
4.3.10 Recurrence Rule
Value Name: RECUR
Not in iCal-Basic.
4.3.11 Text
Value Name: TEXT
Purpose This value type is used to identify values that contain human
readable text.
Formal Definition: The character sets supported by this revision of
iCalendar are UTF-8 and US ASCII thereof. The applicability to other
character sets is for future work. The value type is defined by the
following notation.
text = *(TSAFE-CHAR / ":" / DQUOTE / ESCAPED-CHAR)
; Folded according to description above
ESCAPED-CHAR = "\\" / "\;" / "\," / "\N" / "\n")
; \\ encodes \, \N or \n encodes newline
; \; encodes ;, \, encodes ,
TSAFE-CHAR = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B
%x5D-7E / NON-US-ASCII
; Any character except CTLs not needed by the current
; character set, DQUOTE, ";", ":", "\", ","
Note: Certain other character sets may require modification of the
above definitions, but this is beyond the scope of this document.
Description: If the property permits, multiple "text" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values.
The language in which the text is represented can be controlled by
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the "LANGUAGE" property parameter.
An intentional formatted text line break MUST only be included in a
"TEXT" property value by representing the line break with the
character sequence of BACKSLASH (US-ASCII decimal 92), followed by a
LATIN SMALL LETTER N (US-ASCII decimal 110) or a LATIN CAPITAL LETTER
N (US-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 COMMA character for lists
of values or a SEMICOLON character for structured values. In order
to support the inclusion of these special characters in "TEXT"
property values, they MUST be escaped with a BACKSLASH character. A
BACKSLASH character (US-ASCII decimal 92) in a "TEXT" property value
MUST be escaped with another BACKSLASH character. A COMMA character
in a "TEXT" property value MUST be escaped with a BACKSLASH character
(US-ASCII decimal 92). A SEMICOLON character in a "TEXT" property
value MUST be escaped with a BACKSLASH character (US-ASCII decimal
92). However, a COLON character in 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\nConference Room - 3B\nCome Prepared.
4.3.12 Time
Value Name: TIME
Purpose: This value type is used to identify values that contain a
time of day.
Formal Definition: The data type is defined by the following
notation:
time = 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 account for "leap" seconds.
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time-utc = "Z"
Description: If the property permits, multiple "time" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. No additional content value encoding (i.e., BACKSLASH
character encoding) is defined for this value type.
The "TIME" data type is used to identify values that contain a time
of day. The format is based on the [4] complete representation,
basic format for a time of day. The text format consists 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 0-60). The seconds value of 60 MUST only to be used to
account for "leap" seconds. Fractions of a second are not supported
by this format.
In parallel to the "DATE-TIME" definition above, the "TIME" data type
expresses time values in three forms:
The form of time with UTC offset MUST NOT be used. For example, the
following is NOT VALID for a time value:
230000-0800 ;Invalid time format
FORM #1 LOCAL TIME
The local time form is simply a time value that does not contain the
UTC designator nor does it reference a time zone. For example, 11:00
PM:
230000
Time values of this type are said to be "floating" and are not bound
to any time zone in particular. They are used to represent the same
hour, minute, and second value regardless of which time zone is
currently being observed. For example, an event can be defined that
indicates that an individual will be busy from 11:00 AM to 1:00 PM
every day, no matter which time zone the person is in. In these
cases, a local time can be specified. The recipient of an iCalendar
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 time zone the ATTENDEE is in at any given moment.
This means that two ATTENDEEs may participate in the 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, UTC time MUST be specified. Time
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zones are not in iCal-Basic and may be added in a future extension.
FORM #2: UTC TIME
UTC time, or absolute time, is identified by a LATIN CAPITAL LETTER Z
suffix character (US-ASCII decimal 90), the UTC designator, appended
to the time value. For example, the following represents 07:00 AM
UTC:
070000Z
FORM #3: LOCAL TIME AND TIME ZONE REFERENCE
Are not supported or needed in iCal-Basic implementations. Time zone
information is needed only when including recurring rules and they
may be added at a later time.
Example: The following represents 8:30 AM in New York in Winter, five
hours behind UTC, in each of the two formats using the "X- TIMEOFDAY"
non-standard property:
X-TIMEOFDAY:083000
X-TIMEOFDAY:133000Z
4.3.13 URI
Value Name: URI
Purpose: This value type is used to identify values that contain a
uniform resource identifier (URI) type of reference to the property
value.
Formal Definition: The data type is defined by the following
notation:
uri = <As defined by any IETF RFC>
Description: This data type might be used to reference binary
information, for values that are large, or otherwise undesirable to
include directly in the iCalendar object.
The URI value formats in RFC 1738, RFC 2111 and any other IETF
registered value format can be specified.
Any IANA registered URI format can be used. These include, but are
not limited to, those defined in RFC 1738 and RFC 2111.
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When a property parameter value is a URI value type, the URI MUST be
specified as a quoted-string value.
No additional content value 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
Not needed unil recurrence rules are added.
4.4 iCalendar Object
The Calendaring and Scheduling Core Object is a collection of
calendaring and scheduling information. Typically, this information
will consist of a single iCalendar object. However, multiple
iCalendar objects can be sequentially grouped together. The first
line and last line of the iCalendar object MUST contain a pair of
iCalendar object delimiter strings. The syntax for an iCalendar
object is as follows:
icalobject = 1*("BEGIN" ":" "VCALENDAR" CRLF
icalbody
"END" ":" "VCALENDAR" CRLF)
The following is a simple example of an iCalendar object:
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
BEGIN:VEVENT
DTSTART:19970714T170000Z
DURATION:PT3H30M
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR
4.5 Property
A property is the definition of an individual attribute describing a
calendar or a calendar component. A property takes the form defined
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by the "contentline" notation defined in section 4.1.1.
The following is an example of a property:
DTSTART:19960415T133000Z
This memo imposes no ordering of properties within an iCalendar
object.
Property names, parameter names and enumerated parameter values are
case insensitive. For example, the property name "DUE" is the same
as "due" and "Due", DTSTART:19980714T120000 is the same as DtStart:
19980714T120000.
4.6 Calendar Components
The body of the iCalendar object consists of a sequence of calendar
properties and one or more calendar components. The calendar
properties are attributes that apply to the calendar as a whole. The
calendar components are collections of properties that express a
particular calendar semantic. For example, the calendar component
can specify an event entry, free/busy time information, or an alarm.
The body of the iCalendar object is defined by the following
notation:
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icalbody = calprops component
calprops = 2*(
; 'prodid' and 'version' are both REQUIRED,
; but MUST NOT occur more than once
prodid /version /
; 'calscale' and 'method' are optional,
; but MUST NOT occur more than once
calscale /
method /
x-prop
)
component = 1*(eventc / freebusyc /
/ timezonec / iana-comp / x-comp)
iana-comp = "BEGIN" ":" iana-token CRLF
1*contentline
"END" ":" iana-token CRLF
x-comp = "BEGIN" ":" x-name CRLF
1*contentline
"END" ":" x-name CRLF
An iCalendar object MUST include the "PRODID" and "VERSION" calendar
properties. In addition, it MUST include at least one calendar
component. Special forms of iCalendar objects are possible to
publish just busy time (i.e., only a "VFREEBUSY" calendar component)
information. In addition, a complex iCalendar object is possible
that is used to capture a complete snapshot of the contents of a
calendar (e.g., composite of many different calendar components).
More commonly, an iCalendar object will consist of just a single
"VEVENT" calendar component.
4.6.1 Event Component
Component Name: "VEVENT"
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Purpose: Provide a grouping of component properties that describe an
event.
Format Definition: A "VEVENT" calendar component is defined by the
following notation:
eventc = "BEGIN" ":" "VEVENT" CRLF
eventprop *alarmc
"END" ":" "VEVENT" CRLF
eventprop = *(
; the following are optional,
; but MUST NOT occur more than once
class / created / description / dtstart /
last-mod / location / organizer / priority /
dtstamp / seq / status / summary / transp /
uid / url / duration
; the following are optional,
; and MAY occur more than once
attach / attendee / categories / comment /
contact / rstatus / related /
resources / x-prop / rdate
)
Description: A "VEVENT" calendar component is a grouping of component
properties, and possibly including "VALARM" calendar components, that
represents a scheduled amount of time on a calendar. For example, it
can be an activity; such as a one-hour long, department meeting from
8:00 AM to 9:00 AM, tomorrow. Generally, an event 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 event can have
its Time Transparency set to "TRANSPARENT" in order to prevent
blocking of the event in searches for busy time.
The "VEVENT" is also the calendar component used to specify an
anniversary or daily reminder within a calendar. These events have a
DATE value type for the "DTSTART" property instead of the default
data type of DATE-TIME. The anniversary type of "VEVENT" can span
more than one date (i.e, "DURATION" property value is set to a value
that is more than 24 hours).
The "DTSTART" property for a "VEVENT" specifies the inclusive start
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of the event. The "DURATION" property for a "VEVENT" calendar
component specifies the non-inclusive end of the event. For cases
where a "VEVENT" calendar component specifies a "DTSTART" property
with a DATE data type but no "DURATION" property, the events non-
inclusive end is the end of the calendar date specified by the
"DTSTART" property. For cases where a "VEVENT" calendar component
specifies a "DTSTART" property with a DATE-TIME data type but no
"DURATION" property, the event ends on the same calendar date and
time of day specified by the "DTSTART" property (It consumes no
time).
The "VEVENT" calendar component cannot be nested within another
calendar component.
Example: The following is an example of the "VEVENT" calendar
component used to represent a meeting that will also be opaque to
searches for busy time:
BEGIN:VEVENT
UID:19970901T130000Z-123401@host.com
DTSTAMP:19970901T130000Z
DTSTART:19970903T163000Z
DURATION:PT3H30M
SUMMARY:Annual Employee Review
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, to searches for busy time:
BEGIN:VEVENT
UID:19970901T130000Z-123402@host.com
DTSTAMP:19970901T1300Z
DTSTART:19970401T163000Z
DURATION:PT7H30M
SUMMARY:Laurel is in sensitivity awareness class.
CLASS:PUBLIC
CATEGORIES:BUSINESS,HUMAN RESOURCES
TRANSP:TRANSPARENT
END:VEVENT
The following is an example of the "VEVENT" calendar component used
to represent an anniversary that will occur once. Since it takes up
no time, it will not appear as opaque in a search for busy time; no
matter what the value of the "TRANSP" property indicates:
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BEGIN:VEVENT
UID:19970901T130000Z-123403@host.com
DTSTAMP:19970901T1300Z
DTSTART:19971102
SUMMARY:Our Blissful Anniversary
CLASS:CONFIDENTIAL
CATEGORIES:ANNIVERSARY,PERSONAL,SPECIAL OCCASION
END:VEVENT
4.6.2 To-do Component
Component Name: VTODO
VTODO is not in iCal-Basic.
4.6.3 Journal Component
Component Name: VJOURNAL
VJOURNAL is not in iCal-Basic.
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:
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freebusyc = "BEGIN" ":" "VFREEBUSY" CRLF
fbprop
"END" ":" "VFREEBUSY" CRLF
fbprop = *(
; the following are optional,
; but MUST NOT occur more than once
contact / dtstart / duration / dtstamp /
organizer / uid / url /
; the following are optional,
; and MAY occur more than once
attendee / comment / freebusy / rstatus / x-prop
)
Description: A "VFREEBUSY" calendar component is a grouping of
component properties that represents either a request for, a reply to
a request for free or busy time information or a published set of
busy time information.
When used to request free/busy time information, the "ATTENDEE"
property specifies the calendar users whose free/busy time is being
requested; the "ORGANIZER" property specifies the calendar user who
is requesting the free/busy time; the "DTSTART" and "DURATION"
properties specify the window of time for which the free/busy time is
being requested; the "UID" and "DTSTAMP" properties are specified to
assist in proper sequencing of multiple free/busy time requests.
When used to reply to a request for free/busy time, the "ATTENDEE"
property specifies the calendar user responding to the free/busy time
request; the "ORGANIZER" property specifies the calendar user that
originally requested the free/busy time; the "FREEBUSY" property
specifies the free/busy time information (if it exists); and the
"UID" and "DTSTAMP" properties are specified to assist in proper
sequencing of multiple free/busy time replies.
When used to publish busy time, the "ORGANIZER" property specifies
the calendar user associated with the published busy time; the
"DTSTART" and "DURATION" properties specify an inclusive time window
that surrounds the busy time information; the "FREEBUSY" property
specifies the published busy time information; and the "DTSTAMP"
property specifies the date/time that iCalendar object was created.
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The "VFREEBUSY" calendar component cannot be nested within another
calendar component. Multiple "VFREEBUSY" calendar components can be
specified within an iCalendar object. This permits the grouping of
Free/Busy information into logical collections, such as monthly
groups of busy time information.
The "VFREEBUSY" calendar component is intended for use in iCalendar
object methods involving requests for free time, requests for busy
time, requests for both free and busy, and the associated replies.
Free/Busy information is represented with the "FREEBUSY" property.
This property provides a terse representation of time periods. One
or more "FREEBUSY" properties can be specified in the "VFREEBUSY"
calendar component.
When present in a "VFREEBUSY" calendar component, the "DTSTART" and
"DURATION" properties SHOULD be specified prior to any "FREEBUSY"
properties. In a free time request, these properties can be used in
combination with the "DURATION" property to represent a request for a
duration of free time within a specified window of time.
Example: The following is an example of a "VFREEBUSY" calendar
component used to request free or busy time information:
BEGIN:VFREEBUSY
ORGANIZER:MAILTO:jane_doe@host1.com
ATTENDEE:MAILTO:john_public@host2.com
DTSTART:19971015T050000Z
DURATION:PT24H
DTSTAMP:19970901T083000Z
END:VFREEBUSY
The following is an example of a "VFREEBUSY" calendar component used
to reply to the request with busy time information:
BEGIN:VFREEBUSY
ORGANIZER:MAILTO:jane_doe@host1.com
ATTENDEE:MAILTO:john_public@host2.com
DTSTAMP:19970901T100000Z
FREEBUSY;VALUE=PERIOD:19971015T050000Z/PT8H30M,
19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M
URL:http://host2.com/pub/busy/jpublic-01.ifb
COMMENT:This iCalendar file contains busy time information for
the next three months.
END:VFREEBUSY
The following is an example of a "VFREEBUSY" calendar component used
to publish busy time information.
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BEGIN:VFREEBUSY
ORGANIZER:jsmith@host.com
DTSTART:19980313T141711Z
DURATION:PT672H
FREEBUSY:19980314T233000Z/19980315T003000Z
FREEBUSY:19980316T153000Z/19980316T163000Z
FREEBUSY:19980318T030000Z/19980318T040000Z
URL:http://www.host.com/calendar/busytime/jsmith.ifb
END:VFREEBUSY
4.6.5 Time Zone Component
Component Name: VTIMEZONE
VTIMEZONE is not in iCal-Basic as it is not needed until recurrence
rules are added. Single instances can be specified in GMT.
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:
alarmc = "BEGIN" ":" "VALARM" CRLF
(audioprop / dispprop / emailprop / procprop)
"END" ":" "VALARM" CRLF
audioprop = 2*(
; 'action' and 'trigger' are both REQUIRED,
; but MUST NOT occur more than once
action / trigger /
; 'duration' and 'repeat' are both optional,
; and MUST NOT occur more than once each,
; but if one occurs, so MUST the other
duration / repeat /
; the following is optional,
; but MUST NOT occur more than once
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attach /
; the following is optional,
; and MAY occur more than once
x-prop
)
dispprop = 3*(
; the following are all REQUIRED,
; but MUST NOT occur more than once
action / description / trigger /
; 'duration' and 'repeat' are both optional,
; and MUST NOT occur more than once each,
; but if one occurs, so MUST the other
duration / repeat /
; the following is optional,
; and MAY occur more than once
*x-prop
)
emailprop = 5*(
; the following are all REQUIRED,
; but MUST NOT occur more than once
action / description / trigger / summary
; 'duration' and 'repeat' are both optional,
; and MUST NOT occur more than once each,
; but if one occurs, so MUST the other
duration / repeat /
; the following is REQUIRED,
; and MAY occur more than once
attendee /
; the following are optional,
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; and MAY occur more than once
attach / x-prop
)
procprop = 3*(
; the following are all REQUIRED,
; but MUST NOT occur more than once
action / attach / trigger /
; 'duration' and 'repeat' are both optional,
; and MUST NOT occur more than once each,
; but if one occurs, so MUST the other
duration / repeat /
; 'description' is optional,
; and MUST NOT occur more than once
description /
; the following is optional,
; and MAY occur more than once
x-prop
)
Description: A "VALARM" calendar component is a grouping of component
properties that is a reminder or alarm for an event. For example, it
may be used to define a reminder for a pending event.
The "VALARM" calendar component MUST include the "ACTION" and
"TRIGGER" properties. The "ACTION" property further constrains the
"VALARM" calendar component in the following ways:
When the action is "AUDIO", the alarm can also include one and only
one "ATTACH" property, which MUST point to a sound resource, which is
rendered when the alarm is triggered.
When the action is "DISPLAY", the alarm MUST also include a
"DESCRIPTION" property, which contains the text to be displayed when
the alarm is triggered.
When the action is "EMAIL", the alarm MUST include a "DESCRIPTION"
property, which contains the text to be used as the message body, a
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"SUMMARY" property, which contains the text to be used as the message
subject, and one or more "ATTENDEE" properties, which contain the
email address of attendees to receive the message. It can also
include one or more "ATTACH" properties, which are intended to be
sent as message attachments. When the alarm is triggered, the email
message is sent.
When the action is "PROCEDURE", the alarm MUST include one and only
one "ATTACH" property, which MUST point to a procedure resource,
which is invoked when the alarm is triggered.
The "VALARM" calendar component MUST only appear within either a
"VEVENT" calendar component. "VALARM" calendar components cannot be
nested. Multiple mutually independent "VALARM" calendar components
can be specified for a single "VEVENT" calendar component.
The "TRIGGER" property specifies when the alarm will be triggered.
The "TRIGGER" property specifies a duration prior to the start of an
event. The "TRIGGER" edge may be explicitly set to be relative to
the "START" or "END" of the event with the "RELATED" parameter of the
"TRIGGER" property. The "TRIGGER" property value type can
alternatively be set to an absolute calendar date and time of day
value.
In an alarm set to trigger on the "START" of an event, the "DTSTART"
property MUST be present in the associated event. In an alarm in a
"VEVENT" calendar component set to trigger on the "END" of the event,
the "DTSTART" and "DURATION" properties MUST be present.
The alarm can be defined such that it triggers repeatedly. A
definition of an alarm with a repeating trigger MUST include both the
"DURATION" and "REPEAT" properties. The "DURATION" property
specifies the delay period, after which the alarm will repeat. The
"REPEAT" property specifies the number of additional repetitions that
the alarm will triggered. This repitition count is in addition to
the initial triggering of the alarm. Both of these properties MUST
be present in order to specify a repeating alarm. If one of these
two properties is absent, then the alarm will not repeat beyond the
initial trigger.
The "ACTION" property is used within the "VALARM" calendar component
to specify the type of action invoked when the alarm is triggered.
The "VALARM" properties provide enough information for a specific
action to be invoked. It is typically the responsibility of a
"Calendar User Agent" (CUA) to deliver the alarm in the specified
fashion. An "ACTION" property value of AUDIO specifies an alarm that
causes a sound to be played to alert the user; DISPLAY specifies an
alarm that causes a text message to be displayed to the user; EMAIL
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specifies an alarm that causes an electronic email message to be
delivered to one or more email addresses; and PROCEDURE specifies an
alarm that causes a procedure to be executed. The "ACTION" property
MUST specify one and only one of these values.
In an AUDIO alarm, if the optional "ATTACH" property is included, it
MUST specify an audio sound resource. The intention is that the
sound will be played as the alarm effect. If an "ATTACH" property is
specified that does not refer to a sound resource, or if the
specified sound resource cannot be rendered (because its format is
unsupported, or because it cannot be retrieved), then the CUA or
other entity responsible for playing the sound may choose a fallback
action, such as playing a built-in default sound, or playing no sound
at all.
In a DISPLAY alarm, the intended alarm effect is for the text value
of the "DESCRIPTION" property to be displayed to the user.
In an EMAIL alarm, the intended alarm effect is for an email message
to be composed and delivered to all the addresses specified by the
"ATTENDEE" properties in the "VALARM" calendar component. The
"DESCRIPTION" property of the "VALARM" calendar component MUST be
used as the body text of the message, and the "SUMMARY" property MUST
be used as the subject text. Any "ATTACH" properties in the "VALARM"
calendar component SHOULD be sent as attachments to the message.
In a PROCEDURE alarm, the "ATTACH" property 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
format that cannot be rendered, then no procedure alarm will be
invoked. If the "DESCRIPTION" property is present, its value
specifies the argument string to be passed to the procedure or
program. "Calendar User Agents" that receive an iCalendar object
with this category of alarm, can disable or allow the "Calendar User"
to disable, or otherwise ignore this type of alarm. While a very
useful alarm capability, the PROCEDURE type of alarm SHOULD be
treated by the "Calendar User Agent" as a potential security risk.
Example: The following example is for a "VALARM" calendar component
that specifies an audio alarm that will sound at a precise time.
BEGIN:VALARM
TRIGGER;VALUE=DATE-TIME:19970317T133000Z
REPEAT:4
DURATION:PT15M
ACTION:AUDIO
ATTACH;FMTTYPE=audio/basic:ftp://host.com/pub/sounds/bell-01.aud
END:VALARM
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The following example is for a "VALARM" calendar component that
specifies a display alarm that will trigger 30 minutes before the
scheduled start of the event of its associated component.
BEGIN:VALARM
TRIGGER:-PT30M
REPEAT:2
DURATION:PT15M
ACTION: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 email alarm that will trigger 2 days before the
scheduled due date/time of its associated component. The email has a
subject, body and attachment link.
BEGIN:VALARM
TRIGGER:-P2D
ACTION:EMAIL
ATTENDEE:MAILTO:john_doe@host.com
SUMMARY:*** REMINDER: SEND AGENDA FOR WEEKLY STAFF MEETING ***
DESCRIPTION:A draft agenda needs to be sent out to the attendees
to the weekly managers meeting (MGR-LIST). Attached is a
pointer the document template for the agenda file.
ATTACH;FMTTYPE=application/binary:http://host.com/templates/agen
da.doc
END:VALARM
The following example is for a "VALARM" calendar component that
specifies a procedural alarm that will trigger at a precise date/time
The alarm will invoke a procedure file.
BEGIN:VALARM
TRIGGER;VALUE=DATE-TIME:19980101T050000Z
ACTION:PROCEDURE
REPEAT:23
DURATION:PT1H
ATTACH;FMTTYPE=application/binary: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
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component. They SHOULD be specified after the "BEGIN:VCALENDAR"
property and prior to any calendar component.
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
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: Property can be specified in an iCalendar object. The
default value is "GREGORIAN".
Description: This memo is based on the Gregorian calendar 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.
Format Definition: The property is defined by the following notation:
calscale = "CALSCALE" calparam ":" calvalue CRLF
calparam = *(";" xparam)
calvalue = "GREGORIAN" / iana-token
Example: The following is an example of this property:
CALSCALE:GREGORIAN
4.7.2 Method
Property Name: METHOD
Purpose: This property defines the iCalendar object method associated
with the calendar object.
Value Type: TEXT
Property Parameters: Non-standard property parameters can be
specified on this property.
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Conformance: The property can be specified in an 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 can only appear once within the iCalendar
object. If either the "METHOD" property or the Content-Type "method"
parameter is specified, then the other MUST also be specified.
No methods are defined by this specification. This is the subject of
other specifications, such as the iCalendar Transport-independent
Interoperability Protocol (iTIP) defined by [3].
If this property is not present in the iCalendar object, then a
scheduling transaction MUST NOT be assumed. In such cases, the
iCalendar object is merely being used to transport a snapshot of some
calendar information; without the intention of conveying a scheduling
semantic.
Format Definition: The property is defined by the following notation:
method = "METHOD" metparam ":" metvalue CRLF
metparam = *(";" xparam)
metvalue = iana-token
Example: The following is a hypothetical example of this property to
convey that the iCalendar object is a request for 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
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property MUST be specified once in an iCalendar
object.
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Description: The vendor of the implementation SHOULD assure that this
is a globally unique identifier; using some technique such as an FPI
value, as defined in [5].
This property SHOULD not be used to alter the interpretation of an
iCalendar object beyond the semantics specified in this memo. For
example, it is not to be used to further the understanding of non-
standard properties.
Format Definition: The property is defined by the following notation:
prodid = "PRODID" pidparam ":" pidvalue CRLF
pidparam = *(";" xparam)
pidvalue = text
;Any text that describes the product and version
;and that is generally assured of being unique.
Example: The following is an example of this property. It does not
imply that English is the default language.
PRODID:-//ABC Corporation//NONSGML My Product//EN
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 required in order to interpret the
iCalendar object.
Value Type: TEXT
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property MUST be specified by an iCalendar object,
but MUST only be specified once.
Description: A value of "2.0" corresponds to this memo.
Format Definition: The property is defined by the following notation:
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version = "VERSION" verparam ":" vervalue CRLF
verparam = *(";" xparam)
vervalue = "2.0" ;This memo
/ maxver
/ (minver ";" maxver)
minver = <A IANA registered iCalendar version identifier>
;Minimum iCalendar version needed to parse the iCalendar object
maxver = <A IANA registered iCalendar version identifier>
;Maximum iCalendar version needed to parse the iCalendar object
Example: The following is an example of this property:
VERSION:2.0
4.8 Component Properties
The following properties can appear within calendar components, as
specified by each component property definition.
4.8.1 New Properties
4.8.1.1 IANA Extensions
The following properties specify descriptive information about
calendar components.
Property Name: EXTENSIONS
Purpose: The existance of this property notifies the recipient that
the sender is conforming to this specification.
Value Type: The default value type for this property is multi valued
TEXT.
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property MUST BE specified in "VCALENDAR" calendar
components that wish to conform to this specification. The property
must exist and may be empty.
Description: The property MUST BE specified within "VCALENDAR"
calendar components and may be empty. An empty value indicates that
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the sender conforms to this specification and no other extensions.
The value is comma separated list of extensions that are supported by
the Organizer.
The format for specifying RFC's is to specify the letters 'RFC' in
upper case followed by the RFC number without a dash. As in
'RFC1234' and not 'RFC-1234'. Non standard extensions MUST start
with "X-" or "x-" as in "x-vendor1-extension1". Support for IETF
drafts is discouraged as they expire and are removed making their
names reusable and with a possible different meaning at a later time.
Format Definition: The property is defined by the following notation:
extensions = "EXTENIONS" extparam ":" text *("," text) CRLF
extparam = *(";" xparam)
Example: The following are examples of this property:
EXTENSION:
EXTENSION:RFC1234,RFC5678
4.8.2 Descriptive Component Properties
The following properties specify descriptive information about
calendar components.
4.8.2.1 Attachment
Property Name: ATTACH
Purpose: The property provides the capability to associate a document
object with a calendar component.
Value Type: The default value type for this property is URI. The
value type can also be set to BINARY to indicate inline binary
encoded content information.
Property Parameters: Non-standard, inline encoding, format type and
value data type property parameters can be specified on this
property.
Conformance: The property can be specified in a "VEVENT" or "VALARM"
calendar components.
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Description: The property can be specified within "VEVENT" or
"VALARM" calendar components. This property can be specified
multiple times within an iCalendar object.
Format Definition: The property is defined by the following notation:
attach = "ATTACH" attparam ":" uri CRLF
attach =/ "ATTACH" attparam ";" "ENCODING" "=" "BASE64"
";" "VALUE" "=" "BINARY" ":" binary
attparam = *(
; the following is optional,
; but MUST NOT occur more than once
(";" fmttypeparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
Example: The following are examples of this property:
ATTACH:CID:jsmith.part3.960817T083000.xyzMail@host1.com
ATTACH;FMTTYPE=application/postscript:ftp://xyzCorp.com/pub/
reports/r-960812.ps
4.8.2.2 Categories
Property Name: CATEGORIES
Purpose: This property defines the categories for a calendar
component.
Value Type: TEXT
Property Parameters: Non-standard and language property parameters
can be specified on this property.
Conformance: The property can be specified within "VEVENT" calendar
components.
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Description: This property is used to specify categories or subtypes
of the calendar component. The categories are useful in searching
for a calendar component of a particular type and category. Within
the "VEVENT" calendar components, more than one category can be
specified as a list of categories separated by the COMMA character
(US-ASCII decimal 44).
Format Definition: The property is defined by the following notation:
categories = "CATEGORIES" catparam ":" text *("," text)
CRLF
catparam = *(
; the following is optional,
; but MUST NOT occur more than once
(";" languageparam ) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
Example: The following are examples of this property:
CATEGORIES:APPOINTMENT,EDUCATION
CATEGORIES:MEETING
4.8.2.3 Classification
Property Name: CLASS
Purpose: This property defines the access classification for a
calendar component.
Value Type: TEXT
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property can be specified once in a "VEVENT"
calendar components.
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Description: An access classification is only one component of the
general security system within a calendar application. It provides a
method of capturing the scope of the access 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 a calendar
system (e.g., calendar user authentication, authorization, access
rights, access role, etc.). Hence, the semantics of the individual
access classifications cannot be 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 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.
Format Definition: The property is defined by the following notation:
class = "CLASS" classparam ":" classvalue CRLF
classparam = *(";" xparam)
classvalue = "PUBLIC" / "PRIVATE" / "CONFIDENTIAL" / iana-token
/ x-name
;Default is PUBLIC
Example: The following is an example of this property:
CLASS:PUBLIC
4.8.2.4 Comment
Property Name: COMMENT
Purpose: This property specifies non-processing information intended
to provide a comment to the calendar user.
Value Type: TEXT
Property Parameters: Non-standard, alternate text representation and
language property parameters can be specified on this property.
Conformance: This property can be specified in "VEVENT" or
"VFREEBUSY" calendar components.
Description: The property can be specified multiple times.
Format Definition: The property is defined by the following notation:
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comment = "COMMENT" commparam ":" text CRLF
commparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" altrepparam) / (";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
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 matter of fact\, the venue for the meeting ought to be at
their site. - - John
The data type for this property is TEXT.
4.8.2.5 Description
Property Name: DESCRIPTION
Purpose: This property provides a more complete description of the
calendar component, than that provided by the "SUMMARY" property.
Value Type: TEXT
Property Parameters: Non-standard, alternate text representation and
language property parameters can be specified on this property.
Conformance: The property can be specified in the "VEVENT" or
"VALARM" calendar components.
Description: This property is used in the "VEVENT" to capture lengthy
textual decriptions associated with the activity.
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 argument
string for a PROCEDURE category of alarm.
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Format Definition: The property is defined by the following notation:
description = "DESCRIPTION" descparam ":" text CRLF
descparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" altrepparam) / (";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
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.
4.8.2.6 Geographic Position
Property Name: GEO
Deprecated.
4.8.2.7 Location
Property Name: LOCATION
Purpose: The property defines the intended venue for the activity
defined by a calendar component.
Value Type: TEXT
Property Parameters: Non-standard, alternate text representation and
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language property parameters can be specified on this property.
Conformance: This property can be specified in "VEVENT" calendar
component.
Description: Specific venues such as conference or meeting rooms may
be explicitly specified using this property. An alternate
representation may be specified that is a URI that points to
directory information with more structured specification of the
location. For example, the 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 [16] for the
location.
Format Definition: The property is defined by the following notation:
location = "LOCATION locparam ":" text CRLF
locparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" altrepparam) / (";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
Example: The following are some examples of this property:
LOCATION:Conference Room - F123, Bldg. 002
LOCATION;ALTREP="http://xyzcorp.com/conf-rooms/f123.vcf":
Conference Room - F123, Bldg. 002
4.8.2.8 Percent Complete
Property Name: PERCENT-COMPLETE
PERCENT-COMPLETE is not in iCal-Basic.
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4.8.2.9 Priority
Property Name: PRIORITY
Purpose: The property defines the relative priority for a calendar
component.
Value Type: INTEGER
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property can be specified in a "VEVENT" calendar
component.
Description: The priority is specified as an integer in the range
zero to nine. A value of zero (US-ASCII decimal 48) specifies an
undefined priority. A value of one (US-ASCII decimal 49) is the
highest priority. A value of two (US-ASCII decimal 50) is the second
highest priority. Subsequent numbers specify a decreasing ordinal
priority. A value of nine (US-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
range of one (US-ASCII decimal 49) to four (US-ASCII decimal 52)
specifies "HIGH" priority. A value of five (US-ASCII decimal 53) is
the normal or "MEDIUM" priority. A value in the range of six (US-
ASCII decimal 54) to nine (US-ASCII decimal 58) is "LOW" priority.
A CUA with a priority schema of "A1", "A2", "A3", "B1", "B2", ...,
"C3" is mapped into this property such that a property value of one
(US-ASCII decimal 49) specifies "A1", a property value of two (US-
ASCII decimal 50) specifies "A2", a property value of three (US-ASCII
decimal 51) specifies "A3", and so forth up to a property value of 9
(US-ASCII decimal 58) specifies "C3".
Other integer values are reserved for future use.
Within a "VEVENT" calendar component, this property specifies a
priority for the event. This property may be useful when more than
one event is scheduled for a given time period.
Format Definition: The property is specified by the following
notation:
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priority = "PRIORITY" prioparam ":" privalue CRLF
;Default is zero
prioparam = *(";" xparam)
privalue = integer ;Must be in the range [0..9]
; All other values are reserved for future use
The following is an example of a property with the highest priority:
PRIORITY:1
The following is an example of a property 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 "PRIORITY" property:
PRIORITY:0
4.8.2.10 Resources
Property Name: RESOURCES
Purpose: This property defines the equipment or resources anticipated
for an activity specified by a calendar entity..
Value Type: TEXT
Property Parameters: Non-standard, alternate text representation and
language property parameters can be specified on this property.
Conformance: This property can be specified in "VEVENT" calendar
component.
Description: The property value is an arbitrary text. More than one
resource can be specified as a list of resources separated by the
COMMA character (US-ASCII decimal 44).
Format Definition: The property is defined by the following notation:
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resources = "RESOURCES" resrcparam ":" text *("," text) CRLF
resrcparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" altrepparam) / (";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
Example: The following is an example of this property:
RESOURCES:EASEL,PROJECTOR,VCR
RESOURCES;LANGUAGE=fr:1 raton-laveur
4.8.2.11 Status
Property Name: STATUS
Purpose: This property defines the overall status or confirmation for
the calendar component.
Value Type: TEXT
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property can be specified in "VEVENT" calendar
components.
Description: In a group scheduled calendar component, the property is
used by the "Organizer" to provide a confirmation of the event to the
"Attendees". For example in a "VEVENT" calendar component, the
"Organizer" can indicate that a meeting is tentative, confirmed or
cancelled.
Format Definition: The property is defined by the following notation:
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;Status values for a "VEVENT"
status = "STATUS" statparam] ":" statvalue CRLF
statparam = *(";" xparam)
statvalue = "TENTATIVE" ;Indicates event is
;tentative.
/ "CONFIRMED" ;Indicates event is
;definite.
/ "CANCELLED" ;Indicates event was
;cancelled.
Example: The following is an example of this property for a "VEVENT"
calendar component:
STATUS:TENTATIVE
4.8.2.12 Summary
Property Name: SUMMARY
Purpose: This property defines a short summary or subject for the
calendar component.
Value Type: TEXT
Property Parameters: Non-standard, alternate text representation and
language property parameters can be specified on this property.
Conformance: The property can be specified in "VEVENT" or "VALARM"
calendar components.
Description: This property is used in the "VEVENT" calendar
components to capture a short, one line summary about the activity
entry.
This property is used in the "VALARM" calendar component to capture
the subject of an EMAIL category of alarm.
Format Definition: The property is defined by the following notation:
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summary = "SUMMARY" summparam ":" text CRLF
summparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" altrepparam) / (";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
Example: The following is an example of this property:
SUMMARY:Department Party
4.8.3 Date and Time Component Properties
The following properties specify date and time related information in
calendar components.
4.8.3.1 Date/Time Completed
Property Name: COMPLETED
COMPLETED is not in iCal-Basic.
4.8.3.2 Date/Time End
Property Name: DTEND
Recommend useing the "DURATION" property and not the "DTEND"
property. The "DURATION" property can also specify an explicit end
date and end date-time.
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 can
be set to a DATE value type.
Property Parameters: Non-standard, value data type, time zone
identifier property parameters can be specified on this property.
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Conformance: This property can be specified in "VEVENT" or
"VFREEBUSY" calendar components.
Description: Within the "VEVENT" calendar component, this property
defines the date and time by which the event ends. The value MUST be
later in time than the value of the "DTSTART" property.
Within the "VFREEBUSY" calendar component, this property defines the
end date and time for the free or busy time information. The time
MUST be specified in the UTC time format. The value MUST be later in
time than the value of the "DTSTART" property.
Format Definition: The property is defined by the following notation:
dtend = "DTEND" dtendparam":" dtendval CRLF
dtendparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" "VALUE" "=" ("DATE-TIME" / "DATE")) /
(";" tzidparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
dtendval = date-time / date
;Value MUST match value type
Example: The following is an example of this property:
DTEND:19960401T235959Z
DTEND;VALUE=DATE:19980704
4.8.3.3 Date/Time Due
Property Name: DUE
DUE is not in iCal-Basic.
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4.8.3.4 Date/Time Start
Property Name: DTSTART
Purpose: This property specifies when the calendar component begins.
Value Type: The default value type is DATE-TIME. The time value MUST
be one of the forms defined for the DATE-TIME value type. The value
type can be set to a DATE value type.
Property Parameters: Non-standard and VALUE data type property
parameters can be specified on this property.
Conformance: This property can be specified in the "VEVENT",
"VFREEBUSY" calendar components.
Description: Within the "VEVENT" calendar component, this property
defines the start date and time for the event. The property is
REQUIRED in "VEVENT" calendar components. Events can have a start
date/time but no end date/time. In that case, the event does not
take up any time.
Within the "VFREEBUSY" calendar component, this property defines the
start date and time for the free or busy time information. The time
MUST be specified in UTC time.
Format Definition: The property is defined by the following notation:
dtstart = "DTSTART" dtstparam ":" dtstval CRLF
dtstparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" "VALUE" "=" ("DATE-TIME" / "DATE")) /
; the following is optional,
; and MAY occur more than once
*(";" xparam)
)
dtstval = date-time / date
;Value MUST match value type
Example: The following is an example of this property:
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DTSTART:19980118T073000Z
4.8.3.5 Duration
Property Name: DURATION
Purpose: The property specifies a positive duration of time.
Value Type: DURATION
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property can be specified in "VEVENT", "VFREEBUSY"
or "VALARM" calendar components.
Description: In a "VEVENT" calendar component the property may be
used to specify a duration of the event, instead of an explicit end
date/time. In a "VFREEBUSY" calendar component the property may be
used to specify the interval of free time being requested.
Format Definition: The property is defined by the following notation:
duration = "DURATION" durparam ":" dur-value CRLF
;consisting of a positive duration of time.
durparam = *(";" xparam)
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
4.8.3.6 Free/Busy Time
Property Name: FREEBUSY
Purpose: The property defines one or more free or busy time
intervals.
Value Type: PERIOD. The date and time values MUST be in an UTC time
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format.
Property Parameters: Non-standard or free/busy time type property
parameters can be specified on this property.
Conformance: The property can be specified in a "VFREEBUSY" calendar
component.
Property Parameter: "FBTYPE" and non-standard parameters can be
specified on this property.
Description: These time periods can be specified as either a start
and end date-time or a start date-time and duration. The date and
time MUST be a UTC time format.
"FREEBUSY" properties within the "VFREEBUSY" calendar component
SHOULD be sorted in ascending order, based on start time and then end
time, with the earliest periods first.
The "FREEBUSY" property can specify more than one value, separated by
the COMMA character (US-ASCII decimal 44). In such cases, the
"FREEBUSY" property values SHOULD all be of the same "FBTYPE"
property parameter type (e.g., all values of a particular "FBTYPE"
listed together in a single property).
Format Definition: The property is defined by the following notation:
freebusy = "FREEBUSY" fbparam ":" fbvalue
CRLF
fbparam = *(
; the following is optional,
; but MUST NOT occur more than once
(";" fbtypeparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
fbvalue = period *["," period]
;Time value MUST be in the UTC time format.
Example: The following are some examples of this property:
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FREEBUSY;FBTYPE=BUSY-UNAVAILABLE:19970308T160000Z/PT8H30M
FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H
FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H,
19970308T230000Z/19970309T000000Z
4.8.3.7 Time Transparency
Property Name: TRANSP
Purpose: This property defines whether an event is transparent or not
to busy time searches.
Value Type: TEXT
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property can be specified once in a "VEVENT"
calendar component.
Description: Time Transparency is the characteristic of an event that
determines whether it appears to consume time on a calendar. Events
that consume actual time for the individual or resource associated
with the calendar SHOULD be recorded as OPAQUE, allowing them to be
detected by free-busy time searches. Other events, which do not take
up the individual's (or resource's) time SHOULD be recorded as
TRANSPARENT, making them invisible to free-busy time searches.
Format Definition: The property is specified by the following
notation:
transp = "TRANSP" tranparam ":" transvalue CRLF
tranparam = *(";" xparam)
transvalue = "OPAQUE" ;Blocks or opaque on busy time searches.
/ "TRANSPARENT" ;Transparent on busy time searches.
;Default value is OPAQUE
Example: The following is an example of this property for an event
that is transparent or does not block on free/busy time searches:
TRANSP:TRANSPARENT
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The following is an example of this property for an event that is
opaque or blocks on free/busy time searches:
TRANSP:OPAQUE
4.8.4 Time Zone Component Properties
Property Name: TZID
TZID is not in iCal-Basic.
4.8.5 Time Zone Name
Property Name: TZNAME
TNAME is not in iCal-Basic.
4.8.6 Time Zone Offset From
Property Name: TZOFFSETFROM
TZOFFSETFROM is not in iCal-Basic.
4.8.7 Time Zone Offset To
Property Name: TZOFFSETTO
TZOFFSETTO is not in iCal-Basic.
4.8.8 Time Zone URL
Property Name: TZURL
TZOFFSETTO is not in iCal-Basic.
4.9 Relationship Component Properties
The following properties specify relationship information in calendar
components.
4.9.1 Attendee
Property Name: ATTENDEE
Purpose: The property defines an "Attendee" within a calendar
component.
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Value Type: CAL-ADDRESS
Property Parameters: Non-standard, language, calendar user type,
group or list membership, participation role, participation status,
RSVP expectation, delegatee, delegator, sent by, common name or
directory entry reference property parameters can be specified on
this property.
Conformance: This property MUST be specified in an iCalendar object
that specifies a group scheduled calendar entity. This property MUST
NOT be specified in an iCalendar object when publishing the calendar
information (e.g., NOT in an iCalendar object that specifies the
publication of a calendar user's busy time, event). This property is
not specified in an iCalendar object that defines calendar entities
that are not group scheduled entities, but are entities only on a
single user's calendar.
Description: The property MUST only be specified within calendar
components to specify participants, non-participants and the chair of
a group scheduled calendar entity. The property is specified within
an "EMAIL" category of the "VALARM" calendar component to specify an
email address that is to receive the email type of iCalendar alarm.
The property parameter CN is for the common or displayable name
associated with the calendar address; ROLE, for the intended role
that the attendee will have in the calendar component; PARTSTAT, for
the status of the attendee's participation; RSVP, for indicating
whether the favor of a reply is requested; CUTYPE, to indicate the
type of calendar user; 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 behalf of the ATTENDEE; and DIR, to indicate the
URI that points to the directory information corresponding to the
attendee. These property parameters can be specified on an
"ATTENDEE" property a "VEVENT" calendar component. They MUST not be
specified in an "ATTENDEE" property in a "VFREEBUSY" or "VALARM"
calendar component. If the LANGUAGE property parameter is specified,
the identified language applies to the CN parameter.
A recipient delegated a request MUST inherit the RSVP and ROLE values
from the attendee that delegated the request to them.
Multiple attendees can be specified by including multiple "ATTENDEE"
properties within the calendar component.
Format Definition: The property is defined by the following notation:
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attendee = "ATTENDEE" attparam ":" cal-address CRLF
attparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" cutypeparam) / (";"memberparam) /
(";" roleparam) / (";" partstatparam) /
(";" rsvpparam) / (";" deltoparam) /
(";" delfromparam) / (";" sentbyparam) /
(";"cnparam) / (";" dirparam) /
(";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
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;PARTSTAT=TENTATIVE;CN=Henry Cabot
:MAILTO:hcabot@host2.com
ATTENDEE;ROLE=REQ-PARTICIPANT;DELEGATED-FROM="MAILTO:bob@host.com"
;PARTSTAT=ACCEPTED;CN=Jane Doe:MAILTO:jdoe@host1.com
The following is an example of this property with a URI to the
directory information associated with the attendee:
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
"delegator" information for an event:
ORGANIZER;CN=John Smith:MAILTO:jsmith@host.com
ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=TENTATIVE;DELEGATED-FROM=
"MAILTO:iamboss@host2.com";CN=Henry Cabot:MAILTO:hcabot@
host2.com
ATTENDEE;ROLE=NON-PARTICIPANT;PARTSTAT=DELEGATED;DELEGATED-TO=
"MAILTO:hcabot@host2.com";CN=The Big Cheese:MAILTO:iamboss
@host2.com
ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=ACCEPTED;CN=Jane Doe
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: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 "Attendee":
ATTENDEE;SENT-BY=MAILTO:jan_doe@host1.com;CN=John Smith:MAILTO:
jsmith@host1.com
4.9.2 Contact
Property Name: CONTACT
Purpose: The property is used to represent contact information or
alternately a reference to contact information associated with the
calendar component.
Value Type: TEXT
Property Parameters: Non-standard, alternate text representation and
language property parameters can be specified on this property.
Conformance: The property can be specified in a "VEVENT" or
"VFREEBUSY" calendar component.
Description: The property value consists of textual contact
information. An alternative representation for the property value
can also be specified that refers to a URI pointing to an alternate
form, such as a vCard [16], for the contact information.
Format Definition: The property is defined by the following notation:
contact = "CONTACT" contparam ":" text CRLF
contparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" altrepparam) / (";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
Example: The following is an example of this property referencing
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textual contact information:
CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234
The following is an example of this property with an alternate
representation of 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 following is an example of this property with an alternate
representation of a MIME body part containing the contact
information, such as a vCard [16] 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 an example of this property referencing a network
resource, such as a vCard [16] object containing the contact
information:
CONTACT;ALTREP="http://host.com/pdi/jdoe.vcf":Jim
Dolittle\, ABC Industries\, +1-919-555-1234
4.9.3 Organizer
Property Name: ORGANIZER
Purpose: The property defines the organizer for a calendar component.
Value Type: CAL-ADDRESS
Property Parameters: Non-standard, language, common name, directory
entry reference, sent by property parameters can be specified on this
property.
Conformance: This property MUST be specified in an iCalendar object
that specifies a group scheduled calendar entity. This property MUST
be specified in an iCalendar object that specifies the publication of
a calendar user's busy time. This property MUST NOT be specified in
an iCalendar object that defines calendar entities that are not group
scheduled entities, but are entities only on a single user's
calendar.
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Description: The property is specified within the "VEVENT" calendar
components to specify the organizer of a group scheduled calendar
entity. The property is specified within the "VFREEBUSY" calendar
component to specify the calendar user requesting the free or busy
time. When publishing a "VFREEBUSY" calendar component, the property
is used to specify the calendar that the published busy time came
from.
The property has the property parameters 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". The non-standard parameters may
also be specified on this property. If the LANGUAGE property
parameter is specified, the identified language applies to the CN
parameter value.
Format Definition: The property is defined by the following notation:
organizer = "ORGANIZER" orgparam ":"
cal-address CRLF
orgparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" cnparam) / (";" dirparam) / (";" sentbyparam) /
(";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
Example: The following is an example of this property:
ORGANIZER;CN=John Smith:MAILTO:jsmith@host1.com
The following is an example of this property 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
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The following is an example of this property used by another calendar
user who is acting on behalf of the organizer, with responses
intended to be sent back to the organizer, not the other calendar
user:
ORGANIZER;SENT-BY="MAILTO:jane_doe@host.com":
MAILTO:jsmith@host1.com
4.9.4 Recurrence ID
Property Name: RECURRENCE-ID
RECURRENCE-ID is not in iCal-Basic.
4.9.5 Related To
Property Name: RELATED-TO
Deprecated.
4.9.6 Uniform Resource Locator
Property Name: URL
Purpose: This property defines a Uniform Resource Locator (URL)
associated with the iCalendar object.
Value Type: URI
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property can be specified once in the "VEVENT" or
"VFREEBUSY" calendar components.
Description: This property may be used in a calendar component to
convey a location where a more dynamic rendition of the calendar
information associated with the calendar component can be found.
This memo does not attempt to standardize the form of the URI, nor
the format of the resource pointed to by the property value. If the
URL property and Content-Location MIME header are both specified,
they MUST point to the same resource.
Format Definition: The property is defined by the following notation:
url = "URL" urlparam ":" uri CRLF
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urlparam = *(";" xparam)
Example: The following is an example of this property:
URL:http://abc.com/pub/calendars/jsmith/mytime.ics
4.9.7 Unique Identifier
Property Name: UID
Purpose: This property defines the persistent, globally unique
identifier for the calendar component.
Value Type: TEXT
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property MUST be specified in the "VEVENT" or
"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 [6] 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
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" calendar component.
This property is an important method for group scheduling
applications to match requests with later replies, modifications or
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deletion requests. Calendaring and scheduling applications MUST
generate this property in "VEVENT" 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.
Format Definition: The property is defined by the following notation:
uid = "UID" uidparam ":" text CRLF
uidparam = *(";" xparam)
Example: The following is an example of this property:
UID:19960401T080045Z-4000F192713-0052@host1.com
4.10 Recurrence Component Properties
In iCal-Basic there are no recurrence rules. To add instances, just
re-issue the component. When all of the instances can not be
described in a single "VEVENT" calendar component, then use the
"METHOD" property with a value of "ADD" to signify that you are
adding ZZone or more instances to an existing UID.
4.10.1 Exception Date/Times
Property Name: EXDATE
EXDATE is not in iCal-Basic
4.10.2 Exception Rule
Property Name: EXRULE
EXRULE is not in iCal-Basic
4.10.3 Recurrence Date/Times
Property Name: RDATE
Purpose: This property defines the list of additional date/times for
a recurrence set.
Value Type: The default value type for this property is DATE-TIME.
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The value type can be set to DATE or PERIOD.
Property Parameters: Non-standard, value data type and time zone
identifier property parameters can be specified on this property.
Conformance: The property can be specified in "VEVENT" calendar
component.
Description: This property can appear to define an aggregate set of
repeating occurrences.
The recurrence dates, if specified, are 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 "RDATE"
properties contained within the iCalendar object. The "DTSTART"
property defines the first instance in the recurrence set. Where
duplicate instances are generated by the "RDATE" properties, only one
recurrence is considered. Duplicate instances are ignored. The
value MUST BE in UTC or have no time zone identifier (localtime).
Format Definition: The property is defined by the following notation:
rdate = "RDATE" rdtparam ":" rdtval *("," rdtval) CRLF
rdtparam = *(
;
; the following are optional,
; but MUST NOT occur more than once
(";" "VALUE" "=" ("DATE-TIME" / "PERIOD"))
; Note that a value type of 'DATE' and 'DATE-TIME' is
; deprecated in order to avoid older end time calculations
; that were not done the same by all implementations.
;
; The following is optional,
; and MAY occur more than once
;
(";" xparam)
)
;
rdtval = period ; MUST BE IN UTC or local time
;Value MUST match value type
If it is the Organizers intention to end an appointment at a specific
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date and time, use the value type of 'period-explicit' (See
Section 4.3.9).
If it is the Organizer intention to end an appointment after a
specific duration of time has elapsed, use the 'period-start' value
type (See Section 4.3.9).
Example: The following are examples of this property:
RDATE;VALUE=PERIOD:19960403T020000Z/19960403T040000Z,
19960404T010000Z/PT3H
4.10.4 Recurrence Rule
Property Name: RRULE
RRULE is not in iCal-Basic
4.11 Alarm Component Properties
The following properties specify alarm information in calendar
components.
4.11.1 Action
Property Name: ACTION
Purpose: This property defines the action to be invoked when an alarm
is triggered.
Value Type: TEXT
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property MUST be specified once in a "VALARM"
calendar component.
Description: Each "VALARM" calendar component has a particular type
of action associated with it. This property specifies the type of
action
Format Definition: The property is defined by the following notation:
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action = "ACTION" actionparam ":" actionvalue CRLF
actionparam = *(";" xparam)
actionvalue = "AUDIO" / "DISPLAY" / "EMAIL" / "PROCEDURE"
/ iana-token / x-name
Example: The following are examples of this property in a "VALARM"
calendar component:
ACTION:AUDIO
ACTION:DISPLAY
ACTION:PROCEDURE
4.11.2 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
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property can 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.
Format Definition: The property is defined by the following notation:
repeatcnt = "REPEAT" repparam ":" integer CRLF
;Default is "0", zero.
repparam = *(";" xparam)
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
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4.11.3 Trigger
Property Name: TRIGGER
Purpose: This property specifies when an alarm will trigger.
Value Type: The default value type is DURATION. The value type can
be set to a DATE-TIME value type, in which case the value MUST
specify a UTC formatted DATE-TIME value.
Property Parameters: Non-standard, value data type, or trigger
relationship property parameters can be specified on this property.
The trigger relationship property parameter MUST only be specified
when the value type is DURATION.
Conformance: This property MUST be specified in 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 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
with the "RELATED" parameter. A value of START will set the alarm to
trigger off the start of the associated event. A value of END will
set the alarm to trigger off the end of the associated event.
Either a positive or negative duration may be specified for the
"TRIGGER" property. An alarm with a positive duration is triggered
after the associated start or end of the event. An alarm with a
negative duration is triggered before the associated start or end of
the event.
The "RELATED" property parameter is not valid if the value type of
the property is set to DATE-TIME (i.e., for an absolute date and time
alarm trigger). If a value type of DATE-TIME is specified, then the
property value MUST be specified in the UTC time format.
If the trigger is set relative to START, then the "DTSTART" property
MUST be present in the associated "VEVENT" calendar component. If an
alarm is specified for an event with the trigger set relative to the
END, then the "DSTART" and "DURATION' properties MUST be present in
the associated "VEVENT" calendar component.
Alarms specified in an event which is defined in terms of a DATE
value type will be triggered relative to 00:00:00 UTC on the
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specified date. For example, if "DTSTART:19980205Z, then the
duration trigger will be relative to19980205T000000Z.
Format Definition: The property is defined by the following notation:
trigger = "TRIGGER" (trigrel / trigabs)
trigrel = *(
; the following are optional,
; but MUST NOT occur more than once
(";" "VALUE" "=" "DURATION") /
(";" trigrelparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
) ":" dur-value
trigabs = 1*(
; the following is REQUIRED,
; but MUST NOT occur more than once
(";" "VALUE" "=" "DATE-TIME") /
; the following is optional,
; and MAY occur more than once
(";" xparam)
) ":" date-time
Example: A trigger set 15 minutes prior to the start of the event.
TRIGGER:-P15M
A trigger set 5 minutes after the end of the event.
TRIGGER;RELATED=END:P5M
A trigger set to an absolute date/time.
TRIGGER;VALUE=DATE-TIME:19980101T050000Z
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4.12 Change Management Component Properties
The following properties specify change management information in
calendar components.
4.12.1 Date/Time Created
Property Name: CREATED
Purpose: This property specifies the date and time that the calendar
information was created by the calendar user agent in the calendar
store.
Note: This is analogous to the creation date and time for a file in
the file system.
Value Type: DATE-TIME
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property can be specified once in "VEVENT" calendar
components.
Description: The date and time is a UTC value.
Format Definition: The property is defined by the following notation:
created = "CREATED" creaparam ":" date-time CRLF
creaparam = *(";" xparam)
Example: The following is an example of this property:
CREATED:19960329T133000Z
4.12.2 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
Property Parameters: Non-standard property parameters can be
specified on this property.
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Conformance: This property MUST be included in the "VEVENT" or
"VFREEBUSY" calendar components.
Description: The value MUST be specified in the UTC time format.
This property is also useful to protocols such as [2] 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
particular calendar data in the calendar store was created and last
modified. This is different than when the iCalendar object
representation of the calendar service information was created or
last modified.
Format Definition: The property is defined by the following notation:
dtstamp = "DTSTAMP" stmparam ":" date-time CRLF
stmparam = *(";" xparam)
Example:
DTSTAMP:19971210T080000Z
4.12.3 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
in the calendar store.
Note: This is analogous to the modification date and time for a
file in the file system.
Value Type: DATE-TIME
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property can be specified in the "VEVENT" calendar
components.
Description: The property value MUST be specified in the UTC time
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format.
Format Definition: The property is defined by the following notation:
last-mod = "LAST-MODIFIED" lstparam ":" date-time CRLF
lstparam = *(";" xparam)
Example: The following is are examples of this property:
LAST-MODIFIED:19960817T133000Z
4.12.4 Sequence Number
Property Name: SEQUENCE
Purpose: This property defines the revision sequence number of the
calendar component within a sequence of revisions.
Value Type: integer
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property can be specified in "VEVENT" calendar
component.
Description: When a calendar component is created, its sequence
number is zero (US-ASCII decimal 48). It is monotonically
incremented by the "Organizer's" CUA each time the "Organizer" makes
a revision to the calendar component. Any change to a component
requires the "SEQUENCE" property value to be incremented.
The "Organizer" includes this property in an iCalendar object that it
sends to an "Attendee" to specify the current version of the calendar
component.
The "Attendee" includes this property in an iCalendar object that it
sends to the "Organizer" to specify the version of the calendar
component that the "Attendee" is referring to.
A change to the sequence number is not the mechanism that an
"Organizer" uses to request a response from the "Attendees". The
"RSVP" parameter on the "ATTENDEE" property is used by the
"Organizer" to indicate that a response from the "Attendees" is
requested.
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Format Definition: This property is defined by the following
notation:
seq = "SEQUENCE" seqparam ":" integer CRLF
; Default is "0"
seqparam = *(";" xparam)
Example: The following is an example of this property for a calendar
component that was just created by the "Organizer".
SEQUENCE:0
The following is an example of this property for a calendar component
that has been revised two different times by the "Organizer".
SEQUENCE:2
4.13 Miscellaneous Component Properties
The following properties specify information about a number of
miscellaneous features of calendar components.
4.13.1 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
Property Parameters: Non-standard and language property parameters
can be specified on this property.
Conformance: This property can 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
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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 can 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 can be any of the other valid
data types.
Format Definition: The property is defined by the following notation:
x-prop = x-name *(";" xparam) [";" languageparam] ":" text CRLF
; Lines longer than 75 octets should be folded
Example: The following might be the ABC vendor's extension for an
audio-clip form of subject property:
X-ABC-MMSUBJ;X-ABC-MMSUBJTYPE=wave:http://load.noise.org/mysubj.wav
4.13.2 Request Status
Property Name: REQUEST-STATUS
Purpose: This property defines the status code returned for a
scheduling request.
Value Type: TEXT
Property Parameters: Non-standard and language property parameters
can be specified on this property.
Conformance: The property can be specified in "VEVENT" or "VFREEBUSY"
calendar component.
Description: This property is used to return status code information
related to the processing of an associated iCalendar object. The
data type for this property is TEXT.
The value consists of a short return status component, a longer
return status description component, and optionally a status-specific
data component. The components of the value are separated by the
SEMICOLON character (US-ASCII decimal 59).
The short return status is a PERIOD character (US-ASCII decimal 46)
separated 3-tuple of integers. For example, "3.1.1". The successive
levels of integers provide for a successive level of status code
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granularity.
The following are initial classes for the return status code.
Individual iCalendar object methods will define specific return
status codes for these classes. In addition, other classes for the
return status code may be defined using the registration process
defined later in this memo.
|==============+===============================================|
| Short Return | Longer Return Status Description |
| Status Code | |
|==============+===============================================|
| 1.xx | Preliminary success. This class of status |
| | of status code indicates that the request has |
| | request has been initially processed but that |
| | completion is pending. |
|==============+===============================================|
| 2.xx | Successful. This class of status code |
| | indicates that the request was completed |
| | successfuly. However, the exact status code |
| | can indicate that a fallback has been taken. |
|==============+===============================================|
| 3.xx | Client Error. This class of status code |
| | indicates that the request was not successful.|
| | The error is 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 of error occurred within the |
| | calendaring and scheduling service, not |
| | directly related to the request itself. |
|==============+===============================================|
Format Definition: The property is defined by the following notation:
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rstatus = "REQUEST-STATUS" rstatparam ":"
statcode ";" statdesc [";" extdata]
rstatparam = *(
; the following is optional,
; but MUST NOT occur more than once
(";" languageparm) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
statcode = 1*DIGIT *("." 1*DIGIT)
;Hierarchical, numeric return status code
statdesc = text
;Textual status description
extdata = 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.
The COMMA and SEMICOLON separator characters in the property value
are BACKSLASH character escaped because they appear in a text value.
The 2.8 status would be returned by iCal-Basic only implementations
as recurring ruules do not exist.
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
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5. iCalendar Object Examples
The following examples are provided as an informational source of
illustrative iCalendar objects consistent with this content type.
The following example specifies a three-day conference that begins at
8:00 AM EDT, September 18, 1996 and end at 6:00 PM EDT, September 20,
1996.
BEGIN:VCALENDAR PRODID:-//xyz Corp//NONSGML PDA Calendar Verson
1.0//EN VERSION:2.0 BEGIN:VEVENT DTSTAMP:19960704T120000Z
UID:uid1@host.com ORGANIZER:MAILTO:jsmith@host.com
DTSTART:19960918T143000Z
DURATION:PT34H
STATUS:CONFIRMED
CATEGORIES:CONFERENCE SUMMARY:Networld+Interop Conference
DESCRIPTION:Networld+Interop Conference
and Exhibit\nAtlanta World Congress Center\n
Atlanta, Georgia
END:VEVENT
END:VCALENDAR
The following example specifies a group scheduled meeting that begin
at 8:30 AM UTC on March 12, 1998 and end at 9:30 AM UTC on March 12,
1998. The "Organizer" has scheduled the meeting with one or more
calendar users in a group.
BEGIN:VCALENDAR
PRODID:-//RDU Software//NONSGML HandCal//EN
VERSION:2.0
BEGIN:VEVENT
DTSTAMP:19980309T231000Z
UID:guid-1.host1.com
ORGANIZER;ROLE=CHAIR:MAILTO:mrbig@host.com
ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT;CUTYPE=GROUP:
MAILTO:employee-A@host.com
DESCRIPTION:Project XYZ Review Meeting
CATEGORIES:MEETING
CLASS:PUBLIC
CREATED:19980309T130000Z
SUMMARY:XYZ Project Review
DTSTART:19980312T083000Z
DURATION:PT1H
LOCATION:1CP Conference Room 4350
END:VEVENT
END:VCALENDAR
The following is an example of an iCalendar object passed in a MIME
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message with a single body part consisting of a "text/calendar"
Content Type.
TO:jsmith@host1.com
FROM:jdoe@host1.com
MIME-VERSION:1.0
MESSAGE-ID:<id3@host1.com>
CONTENT-TYPE:text/calendar
BEGIN:VCALENDAR
METHOD:xyz
VERSION:2.0
PRODID:-//ABC Corporation//NONSGML My Product//EN
BEGIN:VEVENT
DTSTAMP:19970324T1200Z
SEQUENCE:0
UID:uid3@host1.com
ORGANIZER:MAILTO:jdoe@host1.com
ATTENDEE;RSVP=TRUE:MAILTO:jsmith@host1.com
DTSTART:19970324T123000Z
DURATION:PT8H30M
CATEGORIES:MEETING,PROJECT
CLASS:PUBLIC
SUMMARY:Calendaring Interoperability Planning Meeting
DESCRIPTION:Discuss how we can test c&s interoperability\n
using iCalendar and other IETF standards.
LOCATION:LDB Lobby
ATTACH;FMTTYPE=application/postscript:ftp://xyzCorp.com/pub/
conf/bkgrnd.ps
END:VEVENT
END:VCALENDAR
The following is an example of published busy time information. The
iCalendar object might be placed in the network resource
www.host.com/calendar/busytime/jsmith.ifb.
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BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//RDU Software//NONSGML HandCal//EN
BEGIN:VFREEBUSY
ORGANIZER:MAILTO:jsmith@host.com
DTSTART:19980313T141711Z
DURATION:PT24H
FREEBUSY:19980314T233000Z/19980315T003000Z
FREEBUSY:19980316T153000Z/19980316T163000Z
FREEBUSY:19980318T030000Z/19980318T040000Z
URL:http://www.host.com/calendar/busytime/jsmith.ifb
END:VFREEBUSY
END:VCALENDAR
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6. Recommended Practices
These recommended practices should be followed in order to assure
consistent handling of the following cases for an iCalendar object.
1. Content lines longer than 75 octets SHOULD be folded.
2. A calendar entry with a "DTSTART" property but no "DURATION"
property 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
time, it MUST NOT be used to record busy time no matter what the
value for the "TRANSP" property.
3. When the multiple iCalendar object have multiple instances
each having the same start date/time, they should be collapsed to,
and considered as, a single instance when every other property and
parameter value are also the same.
4. When a calendar user receives multiple requests for the same
calendar component (e.g., REQUEST for a "VEVENT" calendar
component) as a result of being on multiple mailing lists
specified by "ATTENDEE" properties in the request, they SHOULD
respond to only one of the requests. The calendar user SHOULD
also specify (using the "MEMBER" parameter of the "ATTENDEE"
property) which mailing list they are a member of.
5. An implementation can truncate a "SUMMARY" property value to
255 characters.
6. If seconds of the minute are not supported by an
implementation, then a value of "00" SHOULD be specified for the
seconds component in a time value.
7. If the value type parameter (VALUE=) contains an unknown value
type, it SHOULD be treated as TEXT.
8. Some possible English values for CATEGORIES property include
"ANNIVERSARY", "APPOINTMENT", "BUSINESS", "EDUCATION", "HOLIDAY",
"MEETING", "MISCELLANEOUS", "NON-WORKING HOURS", "NOT IN OFFICE",
"PERSONAL", "PHONE CALL", "SICK DAY", "SPECIAL OCCASION",
"TRAVEL", "VACATION". Categories can be specified in any
registered language.
9. Some possible English values for RESOURCES property include
"CATERING", "CHAIRS", "COMPUTER PROJECTOR", "EASEL", "OVERHEAD
PROJECTOR", "SPEAKER PHONE", "TABLE", "TV", "VCR", "VIDEO PHONE",
"VEHICLE". Resources can be specified in any registered language.
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10. When comparing objects to determine which is the newest: They
must have the same "UID" property value. If the "UID" properties
values are the same then the one with the larger "SEQUENCE" value
is the newest. If the "UID" and "SEQUENCE" property values are
the same then the one with the newer "DTSTAMP" property value is
the newest. If all three are the same, then the objects are
considered to be of the same age.
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7. Registration of Content Type Elements
This section provides the process for registration of MIME
Calendaring and Scheduling Content Type iCalendar object methods and
new or modified properties.
7.1 Registration of New and Modified iCalendar Object Methods
New MIME Calendaring and Scheduling Content Type iCalendar object
methods are registered by the publication of an IETF Request for
Comments (RFC). Changes to an iCalendar object method are registered
by the publication of a revision of the RFC defining the method.
7.2 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. Non-IANA properties can be used by
bilateral agreement, provided the associated properties names follow
the "X-" convention.
The procedures defined here are designed to allow public comment and
review of new properties, while posing only a small impediment to the
definition of new properties.
Registration of a new property is accomplished by the following
steps.
7.2.1 Define the property
A property is defined by completing the following template.
To: ietf-calendar@imc.org
Subject: Registration of text/calendar MIME property XXX
Property name:
Property purpose:
Property value type(s):
Property parameter (s):
Conformance:
Description:
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Format definition:
Examples:
The meaning of each field in the template is as follows.
Property name: The name of the property, as it will appear in the
body of an text/calendar MIME Content-Type "property: value" line to
the left of the colon ":".
Property purpose: The purpose of the property (e.g., to indicate a
delegate for the event, etc.). Give a short but clear description.
Property value type (s): Any of the valid value types for the
property value needs to be specified. The default value type also
needs to be specified. If a new value type is specified, it needs to
be declared in this section.
Property parameter (s): Any of the valid property parameters for the
property needs to be specified.
Conformance: The calendar components that the property can appear in
needs to be specified.
Description: Any special notes about the property, how it is to be
used, etc.
Format definition: The ABNF for the property definition needs to be
specified.
Examples: One or more examples of instances of the property needs to
be specified.
7.2.2 Post the Property definition
The property description MUST be posted to the new property
discussion list, ietf-calendar@imc.org.
7.2.3 Allow a comment period
Discussion on the new property MUST be allowed to take place on the
list for a minimum of two weeks. Consensus MUST be reached on the
property before proceeding to the next step.
7.2.4 Submit the property for approval
Once the two-week comment period has elapsed, and the proposer is
convinced consensus has been reached on the property, the
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registration application should be submitted to the Method Reviewer
for approval. The Method Reviewer is appointed to the Application
Area Directors and can either accept or reject the property
registration. An accepted registration should be passed on by the
Method Reviewer to the IANA for inclusion in the official IANA method
registry. The registration can be rejected for any of the following
reasons. 1) Insufficient comment period; 2) Consensus not reached; 3)
Technical deficiencies raised on the list or elsewhere have not been
addressed. The Method Reviewer's decision to reject a property can
be appealed by the proposer to the IESG, or the objections raised can
be addressed by the proposer and the property resubmitted.
7.3 Property Change Control
Existing properties can 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 that the original author or any other interested party can
propose a change to an existing property, but that such changes
should only be proposed when there are serious omissions or errors in
the published memo. The Method Reviewer can object to a change if it
is not backward compatible, but is not required to do so.
Property definitions can never be deleted from the IANA registry, but
properties which are no longer believed to be useful can be declared
OBSOLETE by a change to their "intended use" field.
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8. References (BOILERPLATE)
This RFC contained boilerplate in this section which has been moved
to the RFC2223-compliant unnumbered section "References."
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9. Acknowledgments
A hearty thanks to the IETF Calendaring and Scheduling Working Group
and also the following individuals who have participated in the
drafting, review and discussion of this memo:
TODO
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10. Authors' and Chairs' Addresses (BOILERPLATE)
This RFC contained boilerplate in this section which has been moved
to the RFC2223-compliant unnumbered section "Author's Address."
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11. Full Copyright Statement (BOILERPLATE)
This RFC contained boilerplate in this section which has been moved
to the RFC2223-compliant unnumbered section "Full Copyright
Statement."
12. References
[1] Royer, D., "Calendar Access Protocol (CAP)", XXXXX 2005.
[2] Dawson, F., Mansour, S., and S. Silverberg, "iCalendar Message-
based Interoperability Protocol (IMIP)", November 1998.
[3] Silverberg, S., Mansour, S., Dawson, F., and R. Hopson,
"iCalendar Transport-Independent Interoperability Protocol
(iTIP) : Scheduling Events, Busy Time, To-dos and Journal
Entries", November 1998.
[4] "ISO 8601, Data elements and interchange formats-Information
interchange--Representation of dates and times International
Organization for Standardization", June 1988.
[5] "ISO/IEC 9070, Information Technology_SGML Support Facilities--
Registration Procedures for Public Text Owner Identifiers
Second Edition, International Organization for
Standardization", April 1991.
[6] Crocker, D., "Standard for the Format of ARPA Internet Text
Messages", August 1982.
[7] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
Resource Locators (URL", December 1994.
[8] Alvestrand, H., "Tags for the Identification of Languages",
March 1995.
[9] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) - Part One: Format of Internet Message
Bodies", November 1996.
[10] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) - Part Two: Media Types", November 1996.
[11] Freed, N., Klensin, J., and J. Postel, "Multipurpose Internet
Mail Extensions (MIME) - Part Four: Registration Procedures",
January 1997.
[12] Bradner, S., "Key words for use in RFCs to Indicate Requirement
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Levels", March 1997.
[13] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", November 1997.
[14] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
January 1998.
[15] Howes, T., Smith, M., and F. Dawson, "A MIME Content-Type for
Directory Information", September 1998.
[16] Dawson, F. and T. Howes, "vCard MIME Directory Profile",
September 1998.
[17] Olson, A., "Time zone code and data,
ftp://elsie.nci.nih.gov/pub/, updated periodically",
<ftp://elsie.nci.nih.gov/pub/>.
[18] "Internet Mail Consortium, vCalendar - The Electronic
Calendaring and Scheduling Exchange Format
http://www.imc.org/pdi/vcal-10.txt", September 1996,
<http://www.imc.org/pdi/vcal-10.txt>.
Author's Address
Doug Royer
IntelliCal LLC
267 Kentlands Blvd., #3041
Gaithersburg, MD 20878
USA
Phone: +1-208-612-4638
Email: Doug@IntelliCal.net
URI: http://Royer.com
Royer Expires June 27, 2006 [Page 109]
Internet-Draft iCal-Basic December 2005
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