Network Working Group B. Desruisseaux, Ed.
Internet-Draft Oracle
Expires: April 14, 2006 C. Stoner, Ed.
IBM
October 11, 2005
Internet Calendaring and Scheduling Core Object Specification
(iCalendar)
draft-ietf-calsify-rfc2445bis-00
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
Calendar systems export, transport and sometimes even store calendar
information in a standard, interoperable format. This memo defines
the common format for openly exchanging calendaring and scheduling
information across the Internet, known as the iCalendar object
format. An iCalendar object may represent an event, to-do or task,
or journal entry (note).
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Comments are solicited and should be addressed to the working group's
mailing list at ietf-calsify@osafoundation.org and/or the editor.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Related Memos . . . . . . . . . . . . . . . . . . . . . 5
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Document Conventions . . . . . . . . . . . . . . . . . . . . 8
3.1. Formatting Conventions . . . . . . . . . . . . . . . . . 8
4. International Considerations . . . . . . . . . . . . . . . . 10
5. General Syntax . . . . . . . . . . . . . . . . . . . . . . . 11
5.1. Character Set . . . . . . . . . . . . . . . . . . . . . 11
5.2. Case Sensitivity . . . . . . . . . . . . . . . . . . . . 11
5.3. Content Lines . . . . . . . . . . . . . . . . . . . . . 11
5.4. List and Field Separators . . . . . . . . . . . . . . . 14
5.5. Multiple Property Values . . . . . . . . . . . . . . . . 14
5.6. Binary Content . . . . . . . . . . . . . . . . . . . . . 15
5.7. Property Parameter Syntax . . . . . . . . . . . . . . . 15
6. iCalendar Objects . . . . . . . . . . . . . . . . . . . . . . 17
7. Calendar Components . . . . . . . . . . . . . . . . . . . . . 18
7.1. Event Component . . . . . . . . . . . . . . . . . . . . 19
7.2. To-do Component . . . . . . . . . . . . . . . . . . . . 22
7.3. Journal Component . . . . . . . . . . . . . . . . . . . 24
7.4. Free/Busy Component . . . . . . . . . . . . . . . . . . 26
7.5. Time Zone Component . . . . . . . . . . . . . . . . . . 29
7.6. Alarm Component . . . . . . . . . . . . . . . . . . . . 38
8. Properties . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.1. Calendar Properties . . . . . . . . . . . . . . . . . . 45
8.1.1. Calendar Scale . . . . . . . . . . . . . . . . . . . 45
8.1.2. Method . . . . . . . . . . . . . . . . . . . . . . . 46
8.1.3. Product Identifier . . . . . . . . . . . . . . . . . 47
8.1.4. Version . . . . . . . . . . . . . . . . . . . . . . . 48
8.2. Descriptive Component Properties . . . . . . . . . . . . 49
8.2.1. Attachment . . . . . . . . . . . . . . . . . . . . . 49
8.2.2. Categories . . . . . . . . . . . . . . . . . . . . . 50
8.2.3. Classification . . . . . . . . . . . . . . . . . . . 51
8.2.4. Comment . . . . . . . . . . . . . . . . . . . . . . . 52
8.2.5. Description . . . . . . . . . . . . . . . . . . . . . 53
8.2.6. Geographic Position . . . . . . . . . . . . . . . . . 54
8.2.7. Location . . . . . . . . . . . . . . . . . . . . . . 56
8.2.8. Percent Complete . . . . . . . . . . . . . . . . . . 57
8.2.9. Priority . . . . . . . . . . . . . . . . . . . . . . 58
8.2.10. Resources . . . . . . . . . . . . . . . . . . . . . . 59
8.2.11. Free/Busy Time Type . . . . . . . . . . . . . . . . . 60
8.2.12. Participation Status . . . . . . . . . . . . . . . . 61
8.2.13. Status . . . . . . . . . . . . . . . . . . . . . . . 63
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8.2.14. Summary . . . . . . . . . . . . . . . . . . . . . . . 64
8.2.15. Date and Time Component Properties . . . . . . . . . 65
8.2.16. Time Zone Component Properties . . . . . . . . . . . 73
8.2.17. Relationship Component Properties . . . . . . . . . . 77
8.2.18. Calendar User Type . . . . . . . . . . . . . . . . . 86
8.2.19. Directory Entry Reference . . . . . . . . . . . . . . 87
8.2.20. Recurrence ID . . . . . . . . . . . . . . . . . . . . 87
8.2.21. Related To . . . . . . . . . . . . . . . . . . . . . 89
8.2.22. Uniform Resource Locator . . . . . . . . . . . . . . 91
8.2.23. Unique Identifier . . . . . . . . . . . . . . . . . . 91
8.2.24. Relationship Type . . . . . . . . . . . . . . . . . . 93
8.3. Recurrence Component Properties . . . . . . . . . . . . 94
8.3.1. Exception Date/Times . . . . . . . . . . . . . . . . 94
8.3.2. Exception Rule . . . . . . . . . . . . . . . . . . . 95
8.3.3. Recurrence Date/Times . . . . . . . . . . . . . . . . 97
8.3.4. Recurrence Identifier Range . . . . . . . . . . . . . 98
8.3.5. Recurrence Rule . . . . . . . . . . . . . . . . . . . 99
8.4. Alarm Component Properties . . . . . . . . . . . . . . . 110
8.4.1. Action . . . . . . . . . . . . . . . . . . . . . . . 110
8.4.2. Alarm Repeat Count . . . . . . . . . . . . . . . . . 111
8.4.3. Alarm Trigger . . . . . . . . . . . . . . . . . . . . 111
8.5. Alarm Trigger Relationship . . . . . . . . . . . . . . . 114
8.6. Change Management Component Properties . . . . . . . . . 114
8.6.1. Date/Time Created . . . . . . . . . . . . . . . . . . 114
8.6.2. Date/Time Stamp . . . . . . . . . . . . . . . . . . . 115
8.6.3. Last Modified . . . . . . . . . . . . . . . . . . . . 116
8.6.4. Sequence Number . . . . . . . . . . . . . . . . . . . 117
8.7. Miscellaneous Component Properties . . . . . . . . . . . 118
8.7.1. RSVP Expectation . . . . . . . . . . . . . . . . . . 118
8.7.2. Language . . . . . . . . . . . . . . . . . . . . . . 119
8.7.3. Group or List Membership . . . . . . . . . . . . . . 120
8.7.4. Alternate Text Representation . . . . . . . . . . . . 121
8.7.5. Inline Encoding . . . . . . . . . . . . . . . . . . . 121
8.7.6. Format Type . . . . . . . . . . . . . . . . . . . . . 122
8.7.7. Non-standard Properties . . . . . . . . . . . . . . . 123
8.7.8. Request Status . . . . . . . . . . . . . . . . . . . 124
9. iCalendar Object Examples . . . . . . . . . . . . . . . . . . 127
10. Recommended Practices . . . . . . . . . . . . . . . . . . . . 132
11. Registration of Content Type Elements . . . . . . . . . . . . 134
11.1. Registration of New and Modified iCalendar Object
Methods . . . . . . . . . . . . . . . . . . . . . . . . 134
11.2. Registration of New Properties . . . . . . . . . . . . . 134
11.3. Define the property . . . . . . . . . . . . . . . . . . 134
11.4. Post the Property definition . . . . . . . . . . . . . . 136
11.5. Allow a comment period . . . . . . . . . . . . . . . . . 136
11.6. Submit the property for approval . . . . . . . . . . . . 136
11.7. Property Change Control . . . . . . . . . . . . . . . . 136
12. Property Parameters . . . . . . . . . . . . . . . . . . . . . 138
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13. Value Data Types . . . . . . . . . . . . . . . . . . . . . . 139
13.1. Binary . . . . . . . . . . . . . . . . . . . . . . . . . 139
13.2. Boolean . . . . . . . . . . . . . . . . . . . . . . . . 140
13.3. Calendar User Address . . . . . . . . . . . . . . . . . 140
13.4. Date . . . . . . . . . . . . . . . . . . . . . . . . . . 141
13.5. Date-Time . . . . . . . . . . . . . . . . . . . . . . . 141
13.6. Duration . . . . . . . . . . . . . . . . . . . . . . . . 143
13.7. Period of Time . . . . . . . . . . . . . . . . . . . . . 144
13.8. Time Zone Identifier . . . . . . . . . . . . . . . . . . 145
13.9. Recurrence Rule . . . . . . . . . . . . . . . . . . . . 146
13.10. Float . . . . . . . . . . . . . . . . . . . . . . . . . 152
13.11. Integer . . . . . . . . . . . . . . . . . . . . . . . . 152
13.12. Text . . . . . . . . . . . . . . . . . . . . . . . . . . 153
13.13. Time . . . . . . . . . . . . . . . . . . . . . . . . . . 154
13.14. URI . . . . . . . . . . . . . . . . . . . . . . . . . . 156
13.15. UTC Offset . . . . . . . . . . . . . . . . . . . . . . . 157
14. Security Considerations . . . . . . . . . . . . . . . . . . . 159
15. IANA MIME Media Type Registration . . . . . . . . . . . . . . 160
16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 163
17. Normative References . . . . . . . . . . . . . . . . . . . . 163
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 165
Intellectual Property and Copyright Statements . . . . . . . . . 166
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1. Introduction
The use of calendaring and scheduling has grown considerably in the
last decade. Enterprise and inter-enterprise business has become
dependent on rapid scheduling of events and actions using this
information technology. However, the longer term growth of
calendaring and scheduling, is currently limited by the lack of
Internet standards for the message content types that are central to
these knowledgeware applications. This memo is intended to progress
the level of interoperability possible between dissimilar calendaring
and scheduling applications. This memo defines a MIME [5] 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 or a Group
Scheduling product.
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, to-dos and
journal entries. The iCalendar object methods can be used to define
other calendaring and scheduling operations such a requesting for and
replying with free/busy time data. [[Comment.1: Removed forward
reference to ITIP (unnecessary) --Lisa D]]
The memo also includes a formal grammar for the content type based on
the Internet ABNF defined in RFC 2234 [8]. 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.
1.1. Related Memos
Implementers will need to be familiar with several other memos that,
along with this memo, form a framework for Internet calendaring and
scheduling standards. This memo, [ICAL], specifies a core
specification of objects, data types, properties and property
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parameters.
[ITIP] - specifies an interoperability protocol for scheduling
between different implementations;
[IMIP] specifies an Internet email binding for [ITIP].
This memo does not attempt to repeat the specification of concepts or
definitions from these other memos. Where possible, references are
made to the memo that provides for the specification of these
concepts or definitions. [[Comment.2: If we keep this section on
related memos, we have to think about whether ITIP and IMIP are
progressing to Draft at the same time, whether to update those
references and whether to add CalDAV or other references. --Lisa D]]
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2. Overview
This draft section provides a high-level overview of the concepts of
iCalendar and the organization of this document.
An iCalendar object contains a set of calendar properties and a set
of components. Components consist of a set of component properties.
Properties consist of a property name, a set of parameters, and a
property value.
The preliminary material of this document includes the introduction,
this overview, some document conventions and the considerations for
internationalization.
Section 5 provides the general syntax rules used by all of iCalendar,
such as character set, line length and line break rules, and which
characters are separators.
Section 6 defines the iCalendar object itself, and Section 7 covers
the components that appear in iCalendar objects.
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3. Document 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
RFC 2119 [7].
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 RFC 2234 [8].
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.
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. [[Comment.3: This section can
be deleted because it provides practically no information and is not
a normative reference: The format for the iCalendar object is based
on the syntax of the RFC 2425 content type. While the iCalendar
object is not a profile of the RFC 2425 content type, it does reuse a
number of the elements from the RFC 2425 specification. --Lisa D]]
3.1. 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 [ITIP] 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 [ITIP]. Calendar components defined by this memo are
referred to with capitalized, quoted-strings of text. All calendar
components start with the letter "V". For example, "VEVENT" refers
to the event calendar component, "VTODO" refers to the to-do calendar
component and "VJOURNAL" refers to the daily journal calendar
component. Scheduling methods defined by [ITIP] are referred to with
capitalized, quoted-strings of text. For example, "REQUEST" refers
to the method for requesting a scheduling calendar component be
created or modified, "REPLY" refers to the method a recipient of a
request uses to update their status with the "Organizer" of the
calendar component.
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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 "MINUTELY"
value can be used with the "FREQ" component of the "RECUR" data type
to specify repeating components based on an interval of one minute or
more.
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4. 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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5. General Syntax
5.1. Character Set
The default character set for an iCalendar object is UTF-8 as defined
in RFC 2279 [9]. The "charset" Content-Type parameter can be used in
MIME transports to specify any other IANA registered character set.
[[Comment.4: I think we need to say something about interoperability
problems which result from using any other charset. --Lisa D]]
5.2. Case Sensitivity
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.
5.3. 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 the 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.
Figure 1
Can be represented as:
DESCRIPTION:This is a lo
ng description
that exists on a long line.
Figure 2
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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. Content
lines are CRLF-separated. [[Comment.5: Removed reference to 2425
again and simply stated that lines are CRLF-separated --Lisa]]
The following ABNF 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
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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)
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
Figure 3
The property value component of a content line has a format that is
property specific. Refer to the section describing each property for
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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.
5.4. List and Field Separators
Some properties and parameters allow a list of values. Values in a
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
5.5. Multiple Property 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.
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5.6. 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
encoding it into text using the "BASE64" encoding method defined in
[RFC 2045]. 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...]
5.7. Property Parameter Syntax
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:
DESCRIPTION;ALTREP="http://www.wiz.org":The Fall'98 Wild Wizards
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Conference - - Las Vegas, NV, USA
Property parameter values that are not in quoted strings are case
insensitive.
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6. iCalendar Objects
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)
Figure 8
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
DTEND:19970715T035959Z
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR
Figure 9
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7. Calendar Components
The body of an 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, a to-do, a journal entry, time zone
information, or free/busy time information, or an alarm.
The body of the iCalendar object is defined by the following
notation:
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 / todoc / journalc / 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
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Figure 10
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)
or time zone (i.e., only a "VTIMEZONE" 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", "VTODO" or "VJOURNAL" calendar component.
7.1. Event Component
Component Name: VEVENT
Purpose: Provide a grouping of component properties that describe an
event.
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Formal 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 / geo /
last-mod / location / organizer / priority /
dtstamp / seq / status / summary / transp /
uid / url / recurid /
; either 'dtend' or 'duration' may appear in
; a 'eventprop', but 'dtend' and 'duration'
; MUST NOT occur in the same 'eventprop'
dtend / duration /
; the following are optional,
; and MAY occur more than once
attach / attendee / categories / comment /
contact / exdate / exrule / rstatus / related /
resources / rdate / rrule / x-prop
)
Figure 11
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
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DATE value type for the "DTSTART" property instead of the default
data type of DATE-TIME. If such a "VEVENT" has a "DTEND" property,
it MUST be specified as a DATE value also. The anniversary type of
"VEVENT" can span more than one date (i.e, "DTEND" property value is
set to a calendar date after the "DTSTART" property value).
The "DTSTART" property for a "VEVENT" specifies the inclusive start
of the event. For recurring events, it also specifies the very first
instance in the recurrence set. The "DTEND" 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 "DTEND" 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
"DTEND" property, the event ends on the same calendar date and time
of day specified by the "DTSTART" property.
The "VEVENT" calendar component cannot be nested within another
calendar component. However, "VEVENT" calendar components can be
related to each other or to a "VTODO" or to a "VJOURNAL" calendar
component with the "RELATED-TO" property.
Example 1: 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:19970901T1300Z
DTSTART:19970903T163000Z
DTEND:19970903T190000Z
SUMMARY:Annual Employee Review
CLASS:PRIVATE
CATEGORIES:BUSINESS,HUMAN RESOURCES
END:VEVENT
Figure 12
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Example 2: 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
DTEND:19970402T010000Z
SUMMARY:Laurel is in sensitivity awareness class.
CLASS:PUBLIC
CATEGORIES:BUSINESS,HUMAN RESOURCES
TRANSP:TRANSPARENT
END:VEVENT
Figure 13
Example 3: The following is an example of the "VEVENT" calendar
component used to represent an anniversary that will occur annually.
Since it takes up no time, it will not appear as opaque in a search
for busy time; no matter what the value of the "TRANSP" property
indicates:
BEGIN:VEVENT
UID:19970901T130000Z-123403@host.com
DTSTAMP:19970901T1300Z
DTSTART:19971102
SUMMARY:Our Blissful Anniversary
CLASS:CONFIDENTIAL
CATEGORIES:ANNIVERSARY,PERSONAL,SPECIAL OCCASION
RRULE:FREQ=YEARLY
END:VEVENT
Figure 14
7.2. To-do Component
Component Name: VTODO
Purpose: Provide a grouping of calendar properties that describe a
to-do.
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Formal Definition: A "VTODO" calendar component is defined by the
following notation:
todoc = "BEGIN" ":" "VTODO" CRLF
todoprop *alarmc
"END" ":" "VTODO" CRLF
todoprop = *(
; the following are optional,
; but MUST NOT occur more than once
class / completed / created / description / dtstamp /
dtstart / geo / last-mod / location / organizer /
percent / priority / recurid / seq / status /
summary / uid / url /
; either 'due' or 'duration' may appear in
; a 'todoprop', but 'due' and 'duration'
; MUST NOT occur in the same 'todoprop'
due / duration /
; the following are optional,
; and MAY occur more than once
attach / attendee / categories / comment / contact /
exdate / exrule / rstatus / related / resources /
rdate / rrule / x-prop
)
Figure 15
Description: A "VTODO" calendar component is a grouping of component
properties and possibly "VALARM" calendar components that represent
an action-item or assignment. For example, it can be used to
represent an item of work assigned to an individual; such as "turn in
travel expense today".
The "VTODO" calendar component cannot be nested within another
calendar component. However, "VTODO" calendar components can be
related to each other or to a "VTODO" or to a "VJOURNAL" calendar
component with the "RELATED-TO" property.
A "VTODO" calendar component without the "DTSTART" and "DUE" (or
"DURATION") properties specifies a to-do that will be associated with
each successive calendar date, until it is completed.
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Example: The following is an example of a "VTODO" calendar component:
BEGIN:VTODO
UID:19970901T130000Z-123404@host.com
DTSTAMP:19970901T1300Z
DTSTART:19970415T133000Z
DUE:19970416T045959Z
SUMMARY:1996 Income Tax Preparation
CLASS:CONFIDENTIAL
CATEGORIES:FAMILY,FINANCE
PRIORITY:1
STATUS:NEEDS-ACTION
END:VTODO
Figure 16
7.3. Journal Component
Component Name: VJOURNAL
Purpose: Provide a grouping of component properties that describe a
journal entry.
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Formal Definition: A "VJOURNAL" calendar component is defined by the
following notation:
journalc = "BEGIN" ":" "VJOURNAL" CRLF
jourprop
"END" ":" "VJOURNAL" CRLF
jourprop = *(
; the following are optional,
; but MUST NOT occur more than once
class / created / description / dtstart / dtstamp /
last-mod / organizer / recurid / seq / status /
summary / uid / url /
; the following are optional,
; and MAY occur more than once
attach / attendee / categories / comment /
contact / exdate / exrule / related / rdate /
rrule / rstatus / x-prop
)
Figure 17
Description: A "VJOURNAL" calendar component is a grouping of
component properties that represent one or more descriptive text
notes associated with a particular calendar date. The "DTSTART"
property is used to specify the calendar date that the journal entry
is associated with. Generally, it will have a DATE value data type,
but it can also be used to specify a DATE-TIME value data type.
Examples of a journal entry include a daily record of a legislative
body or a journal entry of individual telephone contacts for the day
or an ordered list of accomplishments for the day. The "VJOURNAL"
calendar component can also be used to associate a document with a
calendar date.
The "VJOURNAL" calendar component does not take up time on a
calendar. Hence, it does not play a role in free or busy time
searches - - it is as though it has a time transparency value of
TRANSPARENT. It is transparent to any such searches.
The "VJOURNAL" calendar component cannot be nested within another
calendar component. However, "VJOURNAL" calendar components can be
related to each other or to a "VEVENT" or to a "VTODO" calendar
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component, with the "RELATED-TO" property.
Example: The following is an example of the "VJOURNAL" calendar
component:
BEGIN:VJOURNAL
UID:19970901T130000Z-123405@host.com
DTSTAMP:19970901T1300Z
DTSTART;VALUE=DATE:19970317
SUMMARY:Staff meeting minutes
DESCRIPTION:1. Staff meeting: Participants include Joe\, Lisa
and Bob. Aurora project plans were reviewed. There is currently
no budget reserves for this project. Lisa will escalate to
management. Next meeting on Tuesday.\n
2. Telephone Conference: ABC Corp. sales representative called
to discuss new printer. Promised to get us a demo by Friday.\n
3. Henry Miller (Handsoff Insurance): Car was totaled by tree.
Is looking into a loaner car. 654-2323 (tel).
END:VJOURNAL
Figure 18
7.4. 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.
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Formal Definition: A "VFREEBUSY" calendar component is defined by the
following notation:
freebusyc = "BEGIN" ":" "VFREEBUSY" CRLF
fbprop
"END" ":" "VFREEBUSY" CRLF
fbprop = *(
; the following are optional,
; but MUST NOT occur more than once
contact / dtstart / dtend / duration / dtstamp /
organizer / uid / url /
; the following are optional,
; and MAY occur more than once
attendee / comment / freebusy / rstatus / x-prop
)
Figure 19
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 "DTEND"
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
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the calendar user associated with the published busy time; the
"DTSTART" and "DTEND" 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.
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
"DTEND" 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.
The recurrence properties ("RRULE", "EXRULE", "RDATE", "EXDATE") are
not permitted within a "VFREEBUSY" calendar component. Any recurring
events are resolved into their individual busy time periods using the
"FREEBUSY" property.
Example 1: 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
DTEND:19971016T050000Z
DTSTAMP:19970901T083000Z
END:VFREEBUSY
Figure 20
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Example 2: 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
Figure 21
Example 3: a "VFREEBUSY" calendar component used to publish busy time
information.
BEGIN:VFREEBUSY
ORGANIZER:jsmith@host.com
DTSTART:19980313T141711Z
DTEND:19980410T141711Z
FREEBUSY:19980314T233000Z/19980315T003000Z
FREEBUSY:19980316T153000Z/19980316T163000Z
FREEBUSY:19980318T030000Z/19980318T040000Z
URL:http://www.host.com/calendar/busytime/jsmith.ifb
END:VFREEBUSY
Figure 22
7.5. Time Zone Component
Component Name: VTIMEZONE
Purpose: Provide a grouping of component properties that defines a
time zone.
Formal Definition: A "VTIMEZONE" calendar component is defined by the
following notation:
timezonec = "BEGIN" ":" "VTIMEZONE" CRLF
2*(
; 'tzid' is required, but MUST NOT occur more
; than once
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tzid /
; 'last-mod' and 'tzurl' are optional,
but MUST NOT occur more than once
last-mod / tzurl /
; one of 'standardc' or 'daylightc' MUST occur
..; and each MAY occur more than once.
standardc / daylightc /
; the following is optional,
; and MAY occur more than once
x-prop
)
"END" ":" "VTIMEZONE" CRLF
standardc = "BEGIN" ":" "STANDARD" CRLF
tzprop
"END" ":" "STANDARD" CRLF
daylightc = "BEGIN" ":" "DAYLIGHT" CRLF
tzprop
"END" ":" "DAYLIGHT" CRLF
tzprop = 3*(
; the following are each REQUIRED,
; but MUST NOT occur more than once
dtstart / tzoffsetto / tzoffsetfrom /
; the following are optional,
; and MAY occur more than once
comment / rdate / rrule / tzname / x-prop
)
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Figure 23
Description: A time zone is unambiguously defined by the set of time
measurement rules determined by the governing body for a given
geographic area. These rules describe at a minimum the base offset
from UTC for the time zone, often referred to as the Standard Time
offset. Many locations adjust their Standard Time forward or
backward by one hour, in order to accommodate seasonal changes in
number of daylight hours, often referred to as Daylight Saving Time.
Some locations adjust their time by a fraction of an hour. Standard
Time is also known as Winter Time. Daylight Saving Time is also
known as Advanced Time, Summer Time, or Legal Time in certain
countries. The following table shows the changes in time zone rules
in effect for New York City starting from 1967. Each line represents
a description or rule for a particular observance.
Effective Observance Rule
+-----------+-------------------------+--------+--------------+
| Date | (Date/Time) | Offset | Abbreviation |
+-----------+-------------------------+--------+--------------+
| 1967-* | last Sun in Oct, 02:00 | -0500 | EST |
| | | | |
| 1967-1973 | last Sun in Apr, 02:00 | -0400 | EDT |
| | | | |
| 1974-1974 | Jan 6, 02:00 | -0400 | EDT |
| | | | |
| 1975-1975 | Feb 23, 02:00 | -0400 | EDT |
| | | | |
| 1976-1986 | last Sun in Apr, 02:00 | -0400 | EDT |
| | | | |
| 1987-* | first Sun in Apr, 02:00 | -0400 | EDT |
+-----------+-------------------------+--------+--------------+
Note: The specification of a global time zone registry is not
addressed by this document and is left for future study. However,
implementers may find the Olson time zone database [TZ] a useful
reference. It is an informal, public-domain collection of time zone
information, which is currently being maintained by volunteer
Internet participants, and is used in several operating systems.
This database contains current and historical time zone information
for a wide variety of locations around the globe; it provides a time
zone identifier for every unique time zone rule set in actual use
since 1970, with historical data going back to the introduction of
standard time.
Interoperability between two calendaring and scheduling applications,
especially for recurring events, to-dos or journal entries, is
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dependent on the ability to capture and convey date and time
information in an unambiguous format. The specification of current
time zone information is integral to this behavior.
If present, the "VTIMEZONE" calendar component defines the set of
Standard Time and Daylight Saving Time observances (or rules) for a
particular time zone for a given interval of time. The "VTIMEZONE"
calendar component cannot be nested within other calendar components.
Multiple "VTIMEZONE" calendar components can exist in an iCalendar
object. In this situation, each "VTIMEZONE" MUST represent a unique
time zone definition. This is necessary for some classes of events,
such as airline flights, that start in one time zone and end in
another.
The "VTIMEZONE" calendar component MUST be present if the iCalendar
object contains an RRULE that generates dates on both sides of a time
zone shift (e.g. both in Standard Time and Daylight Saving Time)
unless the iCalendar object intends to convey a floating time (See
Section 13.13 for proper interpretation of floating time). It can be
present if the iCalendar object does not contain such a RRULE. In
addition, if a RRULE is present, there MUST be valid time zone
information for all recurrence instances.
The "VTIMEZONE" calendar component MUST include the "TZID" property
and at least one definition of a standard or daylight component. The
standard or daylight component MUST include the "DTSTART",
"TZOFFSETFROM" and "TZOFFSETTO" properties.
An individual "VTIMEZONE" calendar component MUST be specified for
each unique "TZID" parameter value specified in the iCalendar object.
Each "VTIMEZONE" calendar component consists of a collection of one
or more sub-components that describe the rule for a particular
observance (either a Standard Time or a Daylight Saving Time
observance). The "STANDARD" sub-component consists of a collection
of properties that describe Standard Time. The "DAYLIGHT" sub-
component consists of a collection of properties that describe
Daylight Saving Time. In general this collection of properties
consists of:
the first onset date-time for the observance
the last onset date-time for the observance, if a last onset is
known.
the offset to be applied for the observance
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a rule that describes the day and time when the observance takes
effect
an optional name for the observance
For a given time zone, there may be multiple unique definitions of
the observances over a period of time. Each observance is described
using either a "STANDARD" or "DAYLIGHT" sub-component. The
collection of these sub-components is used to describe the time zone
for a given period of time. The offset to apply at any given time is
found by locating the observance that has the last onset date and
time before the time in question, and using the offset value from
that observance.
The top-level properties in a "VTIMEZONE" calendar component are:
The mandatory "TZID" property is a text value that uniquely
identifies the VTIMZONE calendar component within the scope of an
iCalendar object.
The optional "LAST-MODIFIED" property is a UTC value that specifies
the date and time that this time zone definition was last updated.
The optional "TZURL" property is url value that points to a published
VTIMEZONE definition. TZURL SHOULD refer to a resource that is
accessible by anyone who might need to interpret the object. This
SHOULD NOT normally be a file: URL or other URL that is not widely-
accessible.
The collection of properties that are used to define the STANDARD and
DAYLIGHT sub-components include:
The mandatory "DTSTART" property gives the effective onset date and
local time for the time zone sub-component definition. "DTSTART" in
this usage MUST be specified as a local DATE-TIME value.
The mandatory "TZOFFSETFROM" property gives the UTC offset which is
in use when the onset of this time zone observance begins.
"TZOFFSETFROM" is combined with "DTSTART" to define the effective
onset for the time zone sub-component definition. For example, the
following represents the time at which the observance of Standard
Time took effect in Fall 1967 for New York City:
DTSTART:19671029T020000
TZOFFSETFROM:-0400
Figure 24
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The mandatory "TZOFFSETTO " property gives the UTC offset for the
time zone sub-component (Standard Time or Daylight Saving Time) when
this observance is in use.
The optional "TZNAME" property is the customary name for the time
zone. It may be specified multiple times, to allow for specifying
multiple language variants of the time zone names. This could be
used for displaying dates.
If specified, the onset for the observance defined by the time zone
sub-component is defined by either the "RRULE" or "RDATE" property.
If neither is specified, only one sub-component can be specified in
the "VTIMEZONE" calendar component and it is assumed that the single
observance specified is always in effect.
The "RRULE" property defines the recurrence rule for the onset of the
observance defined by this time zone sub-component. Some specific
requirements for the usage of RRULE for this purpose include:
If observance is known to have an effective end date, the "UNTIL"
recurrence rule parameter MUST be used to specify the last valid
onset of this observance (i.e., the UNTIL date-time will be equal
to the last instance generated by the recurrence pattern). It
MUST be specified in UTC time.
The "DTSTART" and the "TZOFFSETTO" properties MUST be used when
generating the onset date-time values (instances) from the RRULE.
Alternatively, the "RDATE" property can be used to define the onset
of the observance by giving the individual onset date and times.
"RDATE" in this usage MUST be specified as a local DATE-TIME value in
UTC time.
The optional "COMMENT" property is also allowed for descriptive
explanatory text.
Example: The following are examples of the "VTIMEZONE" calendar
component:
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Example 1: Time zone information for the Eastern United States using
"RDATE" property. Note that this is only suitable for a recurring
event that starts on or later than April 6, 1997 at 03:00:00 EDT
(i.e., the earliest effective transition date and time) and ends no
later than April 7, 1998 02:00:00 EST (i.e., latest valid date and
time for EST in this scenario). For example, this can be used for a
recurring event that occurs every Friday, 8am-9:00 AM, starting June
1, 1997, ending December 31, 1997.
BEGIN:VTIMEZONE
TZID:US-Eastern
LAST-MODIFIED:19870101T000000Z
BEGIN:STANDARD
DTSTART:19971026T020000
RDATE:19971026T020000
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19970406T020000
RDATE:19970406T020000
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE
Figure 25
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Example 2: Current time zone rules for the Eastern United States
using a RRULE recurrence pattern. Note that there is no effective
end date to either of the Standard Time or Daylight Time rules. This
information would be valid for a recurring event starting today and
continuing indefinitely.
BEGIN:VTIMEZONE
TZID:US-Eastern
LAST-MODIFIED:19870101T000000Z
TZURL:http://zones.stds_r_us.net/tz/US-Eastern
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE
Figure 26
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Example 3: A fictitious set of rules for the Eastern United States,
where the Daylight Time rule has an effective end date (i.e., after
that date, Daylight Time is no longer observed).
BEGIN:VTIMEZONE
TZID:US- -Fictitious-Eastern
LAST-MODIFIED:19870101T000000Z
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE
Figure 27
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Example 4: A fictitious set of rules for the Eastern United States,
where the first Daylight Time rule has an effective end date. There
is a second Daylight Time rule that picks up where the other left
off.
BEGIN:VTIMEZONE
TZID:US- -Fictitious-Eastern
LAST-MODIFIED:19870101T000000Z
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
BEGIN:DAYLIGHT
DTSTART:19990424T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=4
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE
Figure 28
7.6. 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*(
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; '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
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
)
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emailprop = 5*(
; the following are all REQUIRED,
; but MUST NOT occur more than once
action / description / trigger / summary
; the following is REQUIRED,
; and MAY occur more than once
attendee /
; '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 are optional,
; 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
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x-prop
)
Figure 29
Description: A "VALARM" calendar component is a grouping of component
properties that is a reminder or alarm for an event or a to-do. For
example, it may be used to define a reminder for a pending event or
an overdue to-do.
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
"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" or "VTODO" calendar component. "VALARM" calendar components
cannot be nested. Multiple mutually independent "VALARM" calendar
components can be specified for a single "VEVENT" or "VTODO" 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 or a to-do. The "TRIGGER" edge may be explicitly set to be
relative to the "START" or "END" of the event or to-do with the
"RELATED" parameter of the "TRIGGER" property. The "TRIGGER"
property value type can alternatively be set to an absolute calendar
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date and time of day value.
In an alarm set to trigger on the "START" of an event or to-do, the
"DTSTART" property MUST be present in the associated event or to-do.
In an alarm in a "VEVENT" calendar component set to trigger on the
"END" of the event, either the "DTEND" property MUST be present, or
the "DTSTART" and "DURATION" properties MUST both be present. In an
alarm in a "VTODO" calendar component set to trigger on the "END" of
the to-do, either the "DUE" property MUST be present, or the
"DTSTART" and "DURATION" properties MUST both 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
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.
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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 1: A "VALARM" calendar component that specifies an audio
alarm that will sound at a precise time and repeat 4 more times at 15
minute intervals.
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
Figure 30
Example 2: A "VALARM" calendar component that specifies a display
alarm that will trigger 30 minutes before the scheduled start of the
event or the due date/time of the to-do it is associated with and
will repeat 2 more times at 15 minute intervals:
BEGIN:VALARM
TRIGGER:-PT30M
REPEAT:2
DURATION:PT15M
ACTION:DISPLAY
DESCRIPTION:Breakfast meeting with executive\n
team at 8:30 AM EST.
END:VALARM
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Figure 31
Example 3: A "VALARM" calendar component that specifies an email
alarm that will trigger 2 days before the scheduled due date/time of
a to-do it is associated with. It does not repeat. 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/msword:http://host.com/templates/agen
da.doc
END:VALARM
Figure 32
Example 4: A "VALARM" calendar component that specifies a procedural
alarm that will trigger at a precise date/time and will repeat 23
more times at one hour intervals. The alarm will invoke a procedure
file.
BEGIN:VALARM
TRIGGER;VALUE=DATE-TIME:19980101T050000Z
REPEAT:23
DURATION:PT1H
ACTION:PROCEDURE
ATTACH;FMTTYPE=application/octet-stream:ftp://host.com/novo-
procs/felizano.exe
END:VALARM
Figure 33
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8. Properties
A property is the definition of an individual attribute describing a
calendar or a calendar component. A property takes the form defined
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;TZID=US-Eastern:19980714T120000 is the
same as DtStart;TzID=US-Eastern:19980714T120000.
8.1. Calendar Properties
The Calendar Properties are attributes that apply to the iCalendar
object, as a whole. These properties do not appear within a calendar
component. They SHOULD be specified after the "BEGIN:VCALENDAR"
property and prior to any calendar component.
8.1.1. 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
do 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.
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Formal Definition: The property is defined by the following notation:
calscale = "CALSCALE" calparam ":" calvalue CRLF
calparam = *(";" xparam)
calvalue = "GREGORIAN" / iana-token
Figure 35
Example: The following is an example of this property:
CALSCALE:GREGORIAN
Figure 36
8.1.2. 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.
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 [ITIP].
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.
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Formal 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
Figure 38
8.1.3. 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.
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 [ISO 9070].
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.
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Formal 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.
Figure 39
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
Figure 40
8.1.4. 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.
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Formal Definition: The property is defined by the following notation:
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
8.2. Descriptive Component Properties
The following properties can appear within calendar components, as
specified by each component property definition. These specify
descriptive information about calendar components.
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", "VTODO",
"VJOURNAL" or "VALARM" calendar components.
Description: The property can be specified within "VEVENT", "VTODO",
"VJOURNAL", or "VALARM" calendar components. This property can be
specified multiple times within an iCalendar object.
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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
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", "VTODO"
or "VJOURNAL" calendar components.
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", "VTODO" or "VJOURNAL" calendar components, more than
one category can be specified as a list of categories separated by
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the COMMA character (US-ASCII decimal 44).
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)
)
The following are examples of categories.
CATEGORIES:APPOINTMENT,EDUCATION
CATEGORIES:MEETING
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",
"VTODO" or "VJOURNAL" calendar components.
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
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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.
Formal 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
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", "VTODO",
"VJOURNAL", "VTIMEZONE" or "VFREEBUSY" calendar components.
Description: The property can be specified multiple times.
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Formal Definition: The property is defined by the following notation:
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
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", "VTODO",
"VJOURNAL" or "VALARM" calendar components. The property can be
specified multiple times only within a "VJOURNAL" calendar component.
Description: This property is used in the "VEVENT" and "VTODO" to
capture lengthy textual decriptions associated with the activity.
This property is used in the "VJOURNAL" calendar component to capture
one more textual journal entries.
This property is used in the "VALARM" calendar component to capture
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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.
Formal 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.
8.2.6. Geographic Position
Property Name: GEO
Purpose: This property specifies information related to the global
position for the activity specified by a calendar component.
Value Type: FLOAT. The value MUST be two SEMICOLON separated FLOAT
values.
Property Parameters: Non-standard property parameters can be
specified on this property.
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Conformance: This property can be specified in "VEVENT" or "VTODO"
calendar components.
Description: The property value specifies latitude and longitude, in
that order (i.e., "LAT LON" ordering). The longitude represents the
location east or west of the prime meridian as a positive or negative
real number, respectively. The longitude and latitude values MAY be
specified up to six decimal places, which will allow for accuracy to
within one meter of geographical position. Receiving applications
MUST accept values of this precision and MAY truncate values of
greater precision.
Values for latitude and longitude shall be expressed as decimal
fractions of degrees. Whole degrees of latitude shall be represented
by a two-digit decimal number ranging from 0 through 90. Whole
degrees of longitude shall be represented by a decimal number ranging
from 0 through 180. When a decimal fraction of a degree is
specified, it shall be separated from the whole number of degrees by
a decimal point.
Latitudes north of the equator shall be specified by a plus sign (+),
or by the absence of a minus sign (-), preceding the digits
designating degrees. Latitudes south of the Equator shall be
designated by a minus sign (-) preceding the digits designating
degrees. A point on the Equator shall be assigned to the Northern
Hemisphere.
Longitudes east of the prime meridian shall be specified by a plus
sign (+), or by the absence of a minus sign (-), preceding the digits
designating degrees. Longitudes west of the meridian shall be
designated by minus sign (-) preceding the digits designating
degrees. A point on the prime meridian shall be assigned to the
Eastern Hemisphere. A point on the 180th meridian shall be assigned
to the Western Hemisphere. One exception to this last convention is
permitted. For the special condition of describing a band of
latitude around the earth, the East Bounding Coordinate data element
shall be assigned the value +180 (180) degrees.
Any spatial address with a latitude of +90 (90) or -90 degrees will
specify the position at the North or South Pole, respectively. The
component for longitude may have any legal value.
With the exception of the special condition described above, this
form is specified in Department of Commerce, 1986, Representation of
geographic point locations for information interchange (Federal
Information Processing Standard 70-1): Washington, Department of
Commerce, National Institute of Standards and Technology.
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The simple formula for converting degrees-minutes-seconds into
decimal degrees is:
decimal = degrees + minutes/60 + seconds/3600.
Formal Definition: The property is defined by the following notation:
geo = "GEO" geoparam ":" geovalue CRLF
geoparam = *(";" xparam)
geovalue = float ";" float
;Latitude and Longitude components
Example: The following is an example of this property:
GEO:37.386013;-122.082932
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
language property parameters can be specified on this property.
Conformance: This property can be specified in "VEVENT" or "VTODO"
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 [RFC 2426] for the
location.
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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
8.2.8. Percent Complete
Property Name: PERCENT-COMPLETE
Purpose: This property is used by an assignee or delegatee of a to-do
to convey the percent completion of a to-do to the Organizer.
Value Type: INTEGER
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property can be specified in a "VTODO" calendar
component.
Description: The property value is a positive integer between zero
and one hundred. A value of "0" indicates the to-do has not yet been
started. A value of "100" indicates that the to-do has been
completed. Integer values in between indicate the percent partially
complete.
When a to-do is assigned to multiple individuals, the property value
indicates the percent complete for that portion of the to-do assigned
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to the assignee or delegatee. For example, if a to-do is assigned to
both individuals "A" and "B". A reply from "A" with a percent
complete of "70" indicates that "A" has completed 70% of the to-do
assigned to them. A reply from "B" with a percent complete of "50"
indicates "B" has completed 50% of the to-do assigned to them.
Format Definition: The property is defined by the following notation:
percent = "PERCENT-COMPLETE" pctparam ":" integer CRLF
pctparam = *(";" xparam)
Example: The following is an example of this property to show 39%
completion:
PERCENT-COMPLETE:39
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" or "VTODO"
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.
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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.
Within a "VTODO" calendar component, this property specified a
priority for the to-do. This property is useful in prioritizing
multiple action items for a given time period.
Format Definition: The property is specified by the following
notation:
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
8.2.10. Resources
Property Name: RESOURCES
Purpose: This property defines the equipment or resources anticipated
for an activity specified by a calendar entity..
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Value Type: TEXT
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 "VTODO"
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:
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
8.2.11. Free/Busy Time Type
Parameter Name: FBTYPE
Purpose: To specify the free or busy time 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
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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.
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.
Example: The following is an example of this parameter on a FREEBUSY
property.
FREEBUSY;FBTYPE=BUSY:19980415T133000Z/19980415T170000Z
8.2.12. Participation Status
Parameter Name: PARTSTAT
Purpose: To specify the participation status for the calendar user
specified by the property.
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", "VTODO" or "VJOURNAL". 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.
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Format Definition: The property parameter is defined by the following
notation:
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
; These are the participation statuses for a "VEVENT".
; Default is NEEDS-ACTION
partstatparam /= "PARTSTAT" "="
("NEEDS-ACTION" ; To-do needs action
/ "ACCEPTED" ; To-do accepted
/ "DECLINED" ; To-do declined
/ "TENTATIVE" ; To-do tentatively
; accepted
/ "DELEGATED" ; To-do delegated
/ "COMPLETED" ; To-do completed.
; COMPLETED property has
;date/time completed.
/ "IN-PROCESS" ; To-do in process of
; being completed
/ x-name ; Experimental status
/ iana-token) ; Other IANA registered
; status
; These are the participation statuses for a "VTODO". Default is
; NEEDS-ACTION
partstatparam /= "PARTSTAT" "="
("NEEDS-ACTION" ; Journal needs action
/ "ACCEPTED" ; Journal accepted
/ "DECLINED" ; Journal declined
/ x-name ; Experimental status
/ iana-token) ; Other IANA registered
; status
; These are the participation statuses for a "VJOURNAL".
; Default is NEEDS-ACTION
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Example:
ATTENDEE;PARTSTAT=DECLINED:MAILTO:jsmith@host.com
8.2.13. 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", "VTODO" or
"VJOURNAL" 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. In a "VTODO" calendar component, the "Organizer" can
indicate that an action item needs action, is completed, is in
process or being worked on, or has been cancelled. In a "VJOURNAL"
calendar component, the "Organizer" can indicate that a journal entry
is draft, final or has been cancelled or removed.
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Format Definition: The property is defined by the following notation:
status = "STATUS" statparam] ":" statvalue CRLF
statparam = *(";" xparam)
statvalue = "TENTATIVE" ;Indicates event is
;tentative.
/ "CONFIRMED" ;Indicates event is
;definite.
/ "CANCELLED" ;Indicates event was
;cancelled.
;Status values for a "VEVENT"
statvalue =/ "NEEDS-ACTION" ;Indicates to-do needs action.
/ "COMPLETED" ;Indicates to-do completed.
/ "IN-PROCESS" ;Indicates to-do in process of
/ "CANCELLED" ;Indicates to-do was cancelled.
;Status values for "VTODO".
statvalue =/ "DRAFT" ;Indicates journal is draft.
/ "FINAL" ;Indicates journal is final.
/ "CANCELLED" ;Indicates journal is removed.
;Status values for "VJOURNAL".
Example: The following is an example of this property for a "VEVENT"
calendar component:
STATUS:TENTATIVE
The following is an example of this property for a "VTODO" calendar
component:
STATUS:NEEDS-ACTION
The following is an example of this property for a "VJOURNAL"
calendar component:
STATUS:DRAFT
8.2.14. Summary
Property Name: SUMMARY
Purpose: This property defines a short summary or subject for the
calendar component.
Value Type: TEXT
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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", "VTODO",
"VJOURNAL" or "VALARM" calendar components.
Description: This property is used in the "VEVENT", "VTODO" and
"VJOURNAL" calendar components to capture a short, one line summary
about the activity or journal 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:
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
8.2.15. Date and Time Component Properties
The following properties specify date and time related information in
calendar components.
8.2.15.1. Date/Time Completed
Property Name: COMPLETED
Purpose: This property defines the date and time that a to-do was
actually completed.
Value Type: DATE-TIME
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Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property can be specified in a "VTODO" calendar
component.
Description: The date and time MUST be in a UTC format.
Format Definition: The property is defined by the following notation:
completed = "COMPLETED" compparam ":" date-time CRLF
compparam = *(";" xparam)
Example: The following is an example of this property:
COMPLETED:19960401T235959Z
8.2.15.2. Date/Time End
Property Name: DTEND
Purpose: This property specifies the date and time that a calendar
component ends.
Value Type: The default value type is DATE-TIME. The value type 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.
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.
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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
8.2.15.3. Date/Time Due
Property Name: DUE
Purpose: This property defines the date and time that a to-do is
expected to be completed.
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.
Conformance: The property can be specified once in a "VTODO" calendar
component.
Description: The value MUST be a date/time equal to or after the
DTSTART value, if specified.
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Format Definition: The property is defined by the following notation:
due = "DUE" dueparam":" dueval CRLF
dueparam = *(
; 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)
)
dueval = date-time / date
;Value MUST match value type
Example: The following is an example of this property:
DUE:19980430T235959Z
8.2.15.4. 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, value data type, time zone
identifier property parameters can be specified on this property.
Conformance: This property can be specified in the "VEVENT", "VTODO",
"VFREEBUSY", or "VTIMEZONE" 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
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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.
Within the "VTIMEZONE" calendar component, this property defines the
effective start date and time for a time zone specification. This
property is REQUIRED within each STANDARD and DAYLIGHT part included
in "VTIMEZONE" calendar components and MUST be specified as a local
DATE-TIME without the "TZID" property parameter.
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")) /
(";" tzidparam) /
; 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:
DTSTART:19980118T073000Z
8.2.15.5. Duration
Property Name: DURATION
Purpose: The property specifies a positive duration of time.
Value Type: DURATION
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Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: The property can be specified in "VEVENT", "VTODO",
"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 "VTODO" calendar component the property may be used
to specify a duration for the to-do, instead of an explicit due date/
time. In a "VFREEBUSY" calendar component the property may be used
to specify the interval of free time being requested. In a "VALARM"
calendar component the property may be used to specify the delay
period prior to repeating an alarm.
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
8.2.15.6. 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
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.
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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:
FREEBUSY;FBTYPE=BUSY-UNAVAILABLE:19970308T160000Z/PT8H30M
FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H
FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H,
19970308T230000Z/19970309T000000Z
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8.2.15.7. 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
The following is an example of this property for an event that is
opaque or blocks on free/busy time searches:
TRANSP:OPAQUE
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8.2.16. Time Zone Component Properties
The following properties specify time zone information in calendar
components.
8.2.16.1. Time Zone Identifier
Property Name: TZID
Purpose: This property specifies the text value that uniquely
identifies the "VTIMEZONE" calendar component.
Value Type: TEXT
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property MUST be specified in a "VTIMEZONE"
calendar component.
Description: This is the label by which a time zone calendar
component is referenced by any iCalendar properties whose data type
is either DATE-TIME or TIME and not intended to specify a UTC or a
"floating" time. The presence of the SOLIDUS character (US-ASCII
decimal 47) as a prefix, indicates that this TZID represents an
unique ID in a globally defined time zone registry (when such
registry is defined).
Note: This document does not define a naming convention for time zone
identifiers. Implementers may want to use the naming conventions
defined in existing time zone specifications such as the public-
domain Olson database [TZ]. The specification of globally unique
time zone identifiers is not addressed by this document and is left
for future study.
Format Definition: This property is defined by the following
notation:
tzid = "TZID" tzidpropparam ":" [tzidprefix] text CRLF
tzidpropparam = *(";" xparam)
;tzidprefix = "/"
; Defined previously. Just listed here for reader convenience.
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Example: The following are examples of non-globally unique time zone
identifiers:
TZID:US-Eastern
TZID:California-Los_Angeles
The following is an example of a fictitious globally unique time zone
identifier:
TZID:/US-New_York-New_York
8.2.16.2. Time Zone Name
Property Name: TZNAME
Purpose: This property specifies the customary designation for a time
zone description.
Value Type: TEXT
Property Parameters: Non-standard and language property parameters
can be specified on this property.
Conformance: This property can be specified in a "VTIMEZONE" calendar
component.
Description: This property may be specified in multiple languages; in
order to provide for different language requirements.
Format Definition: This property is defined by the following
notation:
tzname = "TZNAME" tznparam ":" text CRLF
tznparam = *(
; the following is optional,
; but MUST NOT occur more than once
(";" languageparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
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Example: The following are example of this property:
TZNAME:EST
Figure 97
The following is an example of this property when two different
languages for the time zone name are specified:
TZNAME;LANGUAGE=en:EST
TZNAME;LANGUAGE=fr-CA:HNE
8.2.16.3. Time Zone Offset From
Property Name: TZOFFSETFROM
Purpose: This property specifies the offset which is in use prior to
this time zone observance.
Value Type: UTC-OFFSET
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property MUST be specified in a "VTIMEZONE"
calendar component.
Description: This property specifies the offset which is in use prior
to this time observance. It is used to calculate the absolute time
at which the transition to a given observance takes place. This
property MUST only be specified in a "VTIMEZONE" calendar component.
A "VTIMEZONE" calendar component MUST include this property. The
property value is a signed numeric indicating the number of hours and
possibly minutes from UTC. Positive numbers represent time zones
east of the prime meridian, or ahead of UTC. Negative numbers
represent time zones west of the prime meridian, or behind UTC.
Format Definition: The property is defined by the following notation:
tzoffsetfrom = "TZOFFSETFROM" frmparam ":" utc-offset
CRLF
frmparam = *(";" xparam)
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Example: The following are examples of this property:
TZOFFSETFROM:-0500
TZOFFSETFROM:+1345
Figure 100
8.2.16.4. Time Zone Offset To
Property Name: TZOFFSETTO
Purpose: This property specifies the offset which is in use in this
time zone observance.
Value Type: UTC-OFFSET
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property MUST be specified in a "VTIMEZONE"
calendar component.
Description: This property specifies the offset which is in use in
this time zone observance. It is used to calculate the absolute time
for the new observance. The property value is a signed numeric
indicating the number of hours and possibly minutes from UTC.
Positive numbers represent time zones east of the prime meridian, or
ahead of UTC. Negative numbers represent time zones west of the
prime meridian, or behind UTC.
Format Definition: The property is defined by the following notation:
tzoffsetto = "TZOFFSETTO" toparam ":" utc-offset CRLF
toparam = *(";" xparam)
Example: The following are examples of this property:
TZOFFSETTO:-0400
TZOFFSETTO:+1245
Figure 102
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8.2.16.5. Time Zone URL
Property Name: TZURL
Purpose: The TZURL provides a means for a VTIMEZONE component to
point to a network location that can be used to retrieve an up-to-
date version of itself.
Value Type: URI
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property can be specified in a "VTIMEZONE" calendar
component.
Description: The TZURL provides a means for a VTIMEZONE component to
point to a network location that can be used to retrieve an up-to-
date version of itself. This provides a hook to handle changes
government bodies impose upon time zone definitions. Retrieval of
this resource results in an iCalendar object containing a single
VTIMEZONE component and a METHOD property set to PUBLISH.
Format Definition: The property is defined by the following notation:
tzurl = "TZURL" tzurlparam ":" uri CRLF
tzurlparam = *(";" xparam)
Example: The following is an example of this property:
TZURL:http://timezones.r.us.net/tz/US-California-Los_Angeles.ics
8.2.17. Relationship Component Properties
The following properties specify relationship information in calendar
components.
8.2.17.1. Attendee
Property Name: ATTENDEE
Purpose: The property defines an "Attendee" within a calendar
component.
Value Type: CAL-ADDRESS
Property Parameters: Non-standard, language, calendar user type,
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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, to-do or journal).
This property is not specified in an iCalendar object that specifies
only a time zone definition or that defines calendar entities that
are not group scheduled entities, but are entities only on a single
user's calendar.
Description: The property 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 in either a "VEVENT", "VTODO" or "VJOURNAL" 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.
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Format Definition: The property is defined by the following notation:
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)
)
Example: The following are examples of this property's use for a to-
do:
ORGANIZER:MAILTO:jsmith@host1.com
ATTENDEE;MEMBER="MAILTO:DEV-GROUP@host2.com":
MAILTO:joecool@host2.com
ATTENDEE;DELEGATED-FROM="MAILTO:immud@host3.com":
MAILTO:janedoe@host1.com
The following is an example of this property used for specifying
multiple attendees to an event:
ORGANIZER:MAILTO:jsmith@host1.com
ATTENDEE;ROLE=REQ-PARTICIPANT;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
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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
: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
8.2.17.2. 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", "VTODO",
"VJOURNAL" 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 [RFC 2426], for the contact information.
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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
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 [RFC 2426] 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 [RFC 2426] object containing the contact
information:
CONTACT;ALTREP="http://host.com/pdi/jdoe.vcf":Jim
Dolittle\, ABC Industries\, +1-919-555-1234
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8.2.17.3. 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 specifies only a time zone definition or
that defines calendar entities that are not group scheduled entities,
but are entities only on a single user's calendar.
Description: The property is specified within the "VEVENT", "VTODO",
"VJOURNAL calendar components to 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.
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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
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
8.2.17.4. Participation Role
Parameter Name: ROLE
Purpose: To specify the participation role for the calendar user
specified by the property.
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter specifies the participation
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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.
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
Example:
ATTENDEE;ROLE=CHAIR:MAILTO:mrbig@host.com
Figure 121
8.2.17.5. Sent By
Parameter Name: SENT-BY
Purpose: To specify the calendar user that is acting on behalf of the
calendar user specified by the property.
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter specifies the calendar user
that is acting on behalf of the calendar user specified by the
property. The parameter value MUST be a MAILTO URI as defined in
[RFC 1738]. The individual calendar address parameter values MUST
each be specified in a quoted-string.
Format Definition: The property parameter is defined by the following
notation:
sentbyparam = "SENT-BY" "=" DQUOTE cal-address DQUOTE
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Example:
ORGANIZER;SENT-BY:"MAILTO:sray@host.com":MAILTO:jsmith@host.com
Figure 123
8.2.17.6. Delegators
Parameter Name: DELEGATED-FROM
Purpose: To specify the calendar users that have delegated their
participation to the calendar user specified by the property.
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. This parameter can be specified on a
property that has a value type of calendar address. This parameter
specifies those calendar uses that have delegated their participation
in a group scheduled event or to-do to the calendar user specified by
the property. The value MUST be a MAILTO URI as defined in [RFC
1738]. The individual calendar address parameter values MUST each be
specified in a quoted-string.
Format Definition: The property parameter is defined by the following
notation:
delfromparam = "DELEGATED-FROM" "="
DQUOTE cal-address DQUOTE
*("," DQUOTE cal-address DQUOTE)
Example:
ATTENDEE;DELEGATED-FROM="MAILTO:jsmith@host.com":MAILTO:
jdoe@host.com
Figure 125
8.2.17.7. Delegatees
Parameter Name: DELEGATED-TO
Purpose: To specify the calendar users to whom the calendar user
specified by the property has delegated participation.
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. This parameter specifies those calendar
users whom have been delegated participation in a group scheduled
event or to-do by the calendar user specified by the property. The
value MUST be a MAILTO URI as defined in [RFC 1738]. The individual
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calendar address parameter values MUST each be specified in a quoted-
string.
Format Definition: The property parameter is defined by the following
notation:
deltoparam = "DELEGATED-TO" "=" DQUOTE cal-address DQUOTE
*("," DQUOTE cal-address DQUOTE)
Example:
ATTENDEE;DELEGATED-TO="MAILTO:jdoe@host.com","MAILTO:jqpublic@
host.com":MAILTO:jsmith@host.com
8.2.17.8. Common Name
Parameter Name: CN
Purpose: To specify the common name to be associated with the
calendar user specified by the property.
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.
Format Definition: The property parameter is defined by the following
notation:
cnparam = "CN" "=" param-value
Example:
ORGANIZER;CN="John Smith":MAILTO:jsmith@host.com
8.2.18. Calendar User Type
Parameter Name: CUTYPE
Purpose: To specify the type of calendar user specified by the
property.
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.
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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
Example:
ATTENDEE;CUTYPE=GROUP:MAILTO:ietf-calsch@imc.org
8.2.19. Directory Entry Reference
Parameter Name: DIR
Purpose: To specify reference to a directory entry associated with
the calendar user specified by the property.
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.
Format Definition: The property parameter is defined by the following
notation:
dirparam = "DIR" "=" DQUOTE uri DQUOTE
Example:
ORGANIZER;DIR="ldap://host.com:6666/o=eDABC%20Industries,
c=3DUS??(cn=3DBJim%20Dolittle)":MAILTO:jimdo@host1.com
8.2.20. Recurrence ID
Property Name: RECURRENCE-ID
Purpose: This property is used in conjunction with the "UID" and
"SEQUENCE" property to identify a specific instance of a recurring
"VEVENT", "VTODO" or "VJOURNAL" calendar component. The property
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value is the effective value of the "DTSTART" property of the
recurrence instance.
Value Type: The default value type for this property is DATE-TIME.
The time format can be any of the valid forms defined for a DATE-TIME
value type. See DATE-TIME value type definition for specific
interpretations of the various forms. The value type can be set to
DATE.
Property Parameters: Non-standard property, value data type, time
zone identifier and recurrence identifier range parameters can be
specified on this property.
Conformance: This property can be specified in an iCalendar object
containing a recurring calendar component.
Description: The full range of calendar components specified by a
recurrence set is referenced by referring to just the "UID" property
value corresponding to the calendar component. The "RECURRENCE-ID"
property allows the reference to an individual instance within the
recurrence set.
If the value of the "DTSTART" property is a DATE type value, then the
value MUST be the calendar date for the recurrence instance.
The date/time value is set to the time when the original recurrence
instance would occur; meaning that if the intent is to change a
Friday meeting to Thursday, the date/time is still set to the
original Friday meeting.
The "RECURRENCE-ID" property is used in conjunction with the "UID"
and "SEQUENCE" property to identify a particular instance of a
recurring event, to-do or journal. For a given pair of "UID" and
"SEQUENCE" property values, the "RECURRENCE-ID" value for a
recurrence instance is fixed. When the definition of the recurrence
set for a calendar component changes, and hence the "SEQUENCE"
property value changes, the "RECURRENCE-ID" for a given recurrence
instance might also change.The "RANGE" parameter is used to specify
the effective range of recurrence instances from the instance
specified by the "RECURRENCE-ID" property value. The default value
for the range parameter is the single recurrence instance only. The
value can also be "THISANDPRIOR" to indicate a range defined by the
given recurrence instance and all prior instances or the value can be
"THISANDFUTURE" to indicate a range defined by the given recurrence
instance and all subsequent instances.
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Format Definition: The property is defined by the following notation:
recurid = "RECURRENCE-ID" ridparam ":" ridval CRLF
ridparam = *(
; the following are optional,
; but MUST NOT occur more than once
(";" "VALUE" "=" ("DATE-TIME" / "DATE)) /
(";" tzidparam) / (";" rangeparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
ridval = date-time / date
;Value MUST match value type
Example: The following are examples of this property:
RECURRENCE-ID;VALUE=DATE:19960401
RECURRENCE-ID;RANGE=THISANDFUTURE:19960120T120000Z
Figure 135
8.2.21. Related To
Property Name: RELATED-TO
Purpose: The property is used to represent a relationship or
reference between one calendar component and another.
Value Type: TEXT
Property Parameters: Non-standard and relationship type property
parameters can be specified on this property.
Conformance: The property can be specified one or more times in the
"VEVENT", "VTODO" or "VJOURNAL" calendar components.
Description: The property value consists of the persistent, globally
unique identifier of another calendar component. This value would be
represented in a calendar component by the "UID" property.
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By default, the property value points to another calendar component
that has a PARENT relationship to the referencing object. The
"RELTYPE" property parameter is used to either explicitly state the
default PARENT relationship type to the referenced calendar component
or to override the default PARENT relationship type and specify
either a CHILD or SIBLING relationship. The PARENT relationship
indicates that the calendar component is a subordinate of the
referenced calendar component. The CHILD relationship indicates that
the calendar component is a superior of the referenced calendar
component. The SIBLING relationship indicates that the calendar
component is a peer of the referenced calendar component.
Changes to a calendar component referenced by this property can have
an implicit impact on the related calendar component. For example,
if a group event changes its start or end date or time, then the
related, dependent events will need to have their start and end dates
changed in a corresponding way. Similarly, if a PARENT calendar
component is canceled or deleted, then there is an implied impact to
the related CHILD calendar components. This property is intended
only to provide information on the relationship of calendar
components. It is up to the target calendar system to maintain any
property implications of this relationship.
Format Definition: The property is defined by the following notation:
related = "RELATED-TO" [relparam] ":" text CRLF
relparam = *(
; the following is optional,
; but MUST NOT occur more than once
(";" reltypeparam) /
; the following is optional,
; and MAY occur more than once
(";" xparm)
)
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The following is an example of this property:
RELATED-TO:jsmith.part7.19960817T083000.xyzMail@host3.com
RELATED-TO:19960401-080045-4000F192713-0052@host1.com
Figure 137
8.2.22. 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",
"VTODO", "VJOURNAL" 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
urlparam = *(";" xparam)
Example: The following is an example of this property:
URL:http://abc.com/pub/calendars/jsmith/mytime.ics
Figure 139
8.2.23. Unique Identifier
Property Name: UID
Purpose: This property defines the persistent, globally unique
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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", "VTODO",
"VJOURNAL" 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 [RFC 822] addr-spec. A good method to assure uniqueness is to
put the domain name or a domain literal IP address of the host on
which the identifier was created on the right hand side of the "@",
and on the left hand side, put a combination of the current calendar
date and time of day (i.e., formatted in as a DATE-TIME value) along
with some other currently unique (perhaps sequential) identifier
available on the system (for example, a process id number). Using a
date/time value on the left hand side and a domain name or domain
literal on the right hand side makes it possible to guarantee
uniqueness since no two hosts should be using the same domain name or
IP address at the same time. Though other algorithms will work, it
is RECOMMENDED that the right hand side contain some domain
identifier (either of the host itself or otherwise) such that the
generator of the message identifier can guarantee the uniqueness of
the left hand side within the scope of that domain.
This is the method for correlating scheduling messages with the
referenced "VEVENT", "VTODO", or "VJOURNAL" calendar component.
The full range of calendar components specified by a recurrence set
is referenced by referring to just the "UID" property value
corresponding to the calendar component. The "RECURRENCE-ID"
property allows the reference to an individual instance within the
recurrence set.
This property is an important method for group scheduling
applications to match requests with later replies, modifications or
deletion requests. Calendaring and scheduling applications MUST
generate this property in "VEVENT", "VTODO" and "VJOURNAL" calendar
components to assure interoperability with other group scheduling
applications. This identifier is created by the calendar system that
generates an iCalendar object.
Implementations MUST be able to receive and persist values of at
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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
Figure 141
8.2.24. Relationship Type
Parameter Name: RELTYPE
Purpose: To specify the type of hierarchical relationship associated
with the calendar component specified by the property.
Description: This parameter can be specified on a property that
references another related calendar. The parameter specifies the
hierarchical relationship type of the calendar component referenced
by the property. The parameter value can be PARENT, to indicate that
the referenced calendar component is a superior of calendar
component; CHILD to indicate that the referenced calendar component
is a subordinate of the calendar component; SIBLING to indicate that
the referenced calendar component is a peer of the calendar
component. If this parameter is not specified on an allowable
property, the default relationship type is PARENT.
Format Definition: The property parameter is defined by the following
notation:
reltypeparam = "RELTYPE" "="
("PARENT" ; Parent relationship. Default.
/ "CHILD" ; Child relationship
/ "SIBLING ; Sibling relationship
/ iana-token ; Some other IANA registered
; iCalendar relationship type
/ x-name) ; A non-standard, experimental
; relationship type
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Example:
RELATED-TO;RELTYPE=SIBLING:<19960401-080045-4000F192713
@host.com>
Figure 143
8.3. Recurrence Component Properties
The following properties specify recurrence information in calendar
components.
8.3.1. Exception Date/Times
Property Name: EXDATE
Purpose: This property defines the list of date/time exceptions for a
recurring calendar component.
Value Type: The default value type for this property is DATE-TIME.
The value type can be set to DATE.
Property Parameters: Non-standard, value data type and time zone
identifier property parameters can be specified on this property.
Conformance: This property can be specified in an iCalendar object
that includes a recurring calendar component.
Description: The exception 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 "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
within the iCalendar object. The "DTSTART" property defines the
first instance in the recurrence set. Multiple instances of the
"RRULE" and "EXRULE" properties can also be specified to define more
sophisticated recurrence sets. The final recurrence set is generated
by gathering all of the start date-times generated by any of the
specified "RRULE" and "RDATE" properties, and then excluding any
start date and times which fall within the union of start date and
times generated by any specified "EXRULE" and "EXDATE" properties.
This implies that start date and times within exclusion related
properties (i.e., "EXDATE" and "EXRULE") take precedence over those
specified by inclusion properties (i.e., "RDATE" and "RRULE"). Where
duplicate instances are generated by the "RRULE" and "RDATE"
properties, only one recurrence is considered. Duplicate instances
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are ignored.
The "EXDATE" property can be used to exclude the value specified in
"DTSTART". However, in such cases the original "DTSTART" date MUST
still be maintained by the calendaring and scheduling system because
the original "DTSTART" value has inherent usage dependencies by other
properties such as the "RECURRENCE-ID".
Format Definition: The property is defined by the following notation:
exdate = "EXDATE" exdtparam ":" exdtval *("," exdtval) CRLF
exdtparam = *(
; 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)
)
exdtval = date-time / date
;Value MUST match value type
Example: The following is an example of this property:
EXDATE:19960402T010000Z,19960403T010000Z,19960404T010000Z
Figure 145
8.3.2. Exception Rule
Property Name: EXRULE
Purpose: This property defines a rule or repeating pattern for an
exception to a recurrence set.
Value Type: RECUR
Property Parameters: Non-standard property parameters can be
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specified on this property.
Conformance: This property can be specified in "VEVENT", "VTODO" or
"VJOURNAL" calendar components.
Description: The exception rule, if specified, is used in computing
the recurrence set. The recurrence set is the complete set of
recurrence instances for a calendar component. The recurrence set is
generated by considering the initial "DTSTART" property along with
the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
within the iCalendar object. The "DTSTART" defines the first
instance in the recurrence set. Multiple instances of the "RRULE"
and "EXRULE" properties can also be specified to define more
sophisticated recurrence sets. The final recurrence set is generated
by gathering all of the start date-times generated by any of the
specified "RRULE" and "RDATE" properties, and excluding any start
date and times which fall within the union of start date and times
generated by any specified "EXRULE" and "EXDATE" properties. This
implies that start date and times within exclusion related properties
(i.e., "EXDATE" and "EXRULE") take precedence over those specified by
inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances
are generated by the "RRULE" and "RDATE" properties, only one
recurrence is considered. Duplicate instances are ignored.
The "EXRULE" property can be used to exclude the value specified in
"DTSTART". However, in such cases the original "DTSTART" date MUST
still be maintained by the calendaring and scheduling system because
the original "DTSTART" value has inherent usage dependencies by other
properties such as the "RECURRENCE-ID".
Format Definition: The property is defined by the following notation:
exrule = "EXRULE" exrparam ":" recur CRLF
exrparam = *(";" xparam)
Example: The following are examples of this property. Except every
other week, on Tuesday and Thursday for 4 occurrences:
EXRULE:FREQ=WEEKLY;COUNT=4;INTERVAL=2;BYDAY=TU,TH
Figure 147
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Except daily for 10 occurrences:
EXRULE:FREQ=DAILY;COUNT=10
Except yearly in June and July for 8 occurrences:
EXRULE:FREQ=YEARLY;COUNT=8;BYMONTH=6,7
8.3.3. Recurrence Date/Times
Property Name: RDATE
Purpose: This property defines the list of date/times for a
recurrence set.
Value Type: The default value type for this property is DATE-TIME.
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", "VTODO",
"VJOURNAL" or "VTIMEZONE" calendar components.
Description: This property can appear along with the "RRULE" property
to define an aggregate set of repeating occurrences. When they both
appear in an iCalendar object, the recurring events are defined by
the union of occurrences defined by both the "RDATE" and "RRULE".
The recurrence dates, if specified, 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 "RRULE",
"RDATE", "EXDATE" and "EXRULE" properties contained within the
iCalendar object. The "DTSTART" property defines the first instance
in the recurrence set. Multiple instances of the "RRULE" and
"EXRULE" properties can also be specified to define more
sophisticated recurrence sets. The final recurrence set is generated
by gathering all of the start date/times generated by any of the
specified "RRULE" and "RDATE" properties, and excluding any start
date/times which fall within the union of start date/times generated
by any specified "EXRULE" and "EXDATE" properties. This implies that
start date/times within exclusion related properties (i.e., "EXDATE"
and "EXRULE") take precedence over those specified by inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances
are generated by the "RRULE" and "RDATE" properties, only one
recurrence is considered. Duplicate instances are ignored.
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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" / "DATE" / "PERIOD")) /
(";" tzidparam) /
; the following is optional,
; and MAY occur more than once
(";" xparam)
)
rdtval = date-time / date / period
;Value MUST match value type
Example: The following are examples of this property:
RDATE:19970714T123000Z
RDATE;TZID=US-EASTERN:19970714T083000
RDATE;VALUE=PERIOD:19960403T020000Z/19960403T040000Z,
19960404T010000Z/PT3H
RDATE;VALUE=DATE:19970101,19970120,19970217,19970421
19970526,19970704,19970901,19971014,19971128,19971129,19971225
Figure 151
8.3.4. Recurrence Identifier Range
Parameter Name: RANGE
Purpose: To specify the effective range of recurrence instances from
the instance specified by the recurrence identifier specified by the
property.
Description: The parameter can be specified on a property that
specifies a recurrence identifier. The parameter specifies the
effective range of recurrence instances that is specified by the
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property. The effective range is from the recurrence identified
specified by the property. If this parameter is not specified an
allowed property, then the default range is the single instance
specified by the recurrence identifier value of the property. The
parameter value can be "THISANDPRIOR" to indicate a range defined by
the recurrence identified value of the property and all prior
instances. The parameter value can also be "THISANDFUTURE" to
indicate a range defined by the recurrence identifier and all
subsequent instances.
Format Definition: The property parameter is defined by the following
rangeparam = "RANGE" "=" ("THISANDPRIOR"
; To specify all instances prior to the recurrence identifier
/ "THISANDFUTURE")
; To specify the instance specified by the recurrence identifier
; and all subsequent recurrence instances
Example:
RECURRENCE-ID;RANGE=THISANDPRIOR:19980401T133000Z
Figure 153
8.3.5. Recurrence Rule
Property Name: RRULE
Purpose: This property defines a rule or repeating pattern for
recurring events, to-dos, or time zone definitions.
Value Type: RECUR
Property Parameters: Non-standard property parameters can be
specified on this property.
Conformance: This property can be specified one or more times in
recurring "VEVENT", "VTODO" and "VJOURNAL" calendar components. It
can also be specified once in each STANDARD or DAYLIGHT sub-component
of the "VTIMEZONE" calendar component.
Description: The recurrence rule, if specified, is used in computing
the recurrence set. The recurrence set is the complete set of
recurrence instances for a calendar component. The recurrence set is
generated by considering the initial "DTSTART" property along with
the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
within the iCalendar object. The "DTSTART" property defines the
first instance in the recurrence set. Multiple instances of the
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"RRULE" and "EXRULE" properties can also be specified to define more
sophisticated recurrence sets. The final recurrence set is generated
by gathering all of the start date/times generated by any of the
specified "RRULE" and "RDATE" properties, and excluding any start
date/times which fall within the union of start date/times generated
by any specified "EXRULE" and "EXDATE" properties. This implies that
start date/times within exclusion related properties (i.e., "EXDATE"
and "EXRULE") take precedence over those specified by inclusion
properties (i.e., "RDATE" and "RRULE"). Where duplicate instances
are generated by the "RRULE" and "RDATE" properties, only one
recurrence is considered. Duplicate instances are ignored.
The "DTSTART" and "DTEND" property pair or "DTSTART" and "DURATION"
property pair, specified within the iCalendar object defines the
first instance of the recurrence. When used with a recurrence rule,
the "DTSTART" and "DTEND" properties MUST be specified in local time
and the appropriate set of "VTIMEZONE" calendar components MUST be
included. For detail on the usage of the "VTIMEZONE" calendar
component, see the "VTIMEZONE" calendar component definition.
Any duration associated with the iCalendar object applies to all
members of the generated recurrence set. Any modified duration for
specific recurrences MUST be explicitly specified using the "RDATE"
property.
Format Definition: This property is defined by the following
notation:
rrule = "RRULE" rrulparam ":" recur CRLF
rrulparam = *(";" xparam)
Example: All examples assume the Eastern United States time zone.
Daily for 10 occurrences:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=DAILY;COUNT=10
==> (1997 9:00 AM EDT)September 2-11
Daily until December 24, 1997:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=DAILY;UNTIL=19971224T000000Z
==> (1997 9:00 AM EDT)September 2-30;October 1-25
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(1997 9:00 AM EST)October 26-31;November 1-30;December 1-23
Every other day - forever:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=DAILY;INTERVAL=2
==> (1997 9:00 AM EDT)September2,4,6,8...24,26,28,30;
October 2,4,6...20,22,24
(1997 9:00 AM EST)October 26,28,30;November
1,3,5,7...25,27,29; Dec 1,3,...
Every 10 days, 5 occurrences:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5
==> (1997 9:00 AM EDT)September 2,12,22;
October 2,12
Everyday in January, for 3 years:
DTSTART;TZID=US-Eastern:19980101T090000
RRULE:FREQ=YEARLY;UNTIL=20000131T090000Z;
BYMONTH=1;BYDAY=SU,MO,TU,WE,TH,FR,SA
or
RRULE:FREQ=DAILY;UNTIL=20000131T090000Z;
BYMONTH=1
==> (1998 9:00 AM EDT)January 1-31
(1999 9:00 AM EDT)January 1-31
(2000 9:00 AM EDT)January 1-31
Weekly for 10 occurrences
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=WEEKLY;COUNT=10
==> (1997 9:00 AM EDT)September 2,9,16,23,30;
October 7,14,21
(1997 9:00 AM EST)October 28;November 4
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Weekly until December 24, 1997
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=WEEKLY;UNTIL=19971224T000000Z
==> (1997 9:00 AM EDT)September 2,9,16,23,30;
October 7,14,21(1997 9:00 AM EST)October 28;
November 4,11,18,25;
December 2,9,16,23
Every other week - forever:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;WKST=SU
==> (1997 9:00 AM EDT)September 2,16,30;October 14
(1997 9:00 AM EST)October 28;November 11,25;
December 9,23(1998 9:00 AM EST)January 6,20;February
...
Weekly on Tuesday and Thursday for 5 weeks:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=WEEKLY;UNTIL=19971007T000000Z;
WKST=SU;BYDAY=TU,TH
or
RRULE:FREQ=WEEKLY;COUNT=10;WKST=SU;BYDAY=TU,TH
==> (1997 9:00 AM EDT)September 2,4,9,11,16,18,23,25,30;
October 2
Every other week on Monday, Wednesday and Friday until
December 24, 1997, but starting on Tuesday,
September 2, 1997:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;UNTIL=19971224T000000Z;
WKST=SU;BYDAY=MO,WE,FR
==> (1997 9:00 AM EDT)September 2,3,5,15,17,19,29;October
1,3,13,15,17
(1997 9:00 AM EST)October 27,29,31;
November 10,12,14,24,26,28;
December 8,10,12,22
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Every other week on Tuesday and Thursday, for 8 occurrences:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;
BYDAY=TU,TH
==> (1997 9:00 AM EDT)September 2,4,16,18,30;
October 2,14,16
Monthly on the 1st Friday for ten occurrences:
DTSTART;TZID=US-Eastern:19970905T090000
RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR
==> (1997 9:00 AM EDT)September 5;October 3
(1997 9:00 AM EST)November 7;Dec 5
(1998 9:00 AM EST)January 2;February 6;
March 6;April 3
(1998 9:00 AM EDT)May 1;June 5
Monthly on the 1st Friday until December 24, 1997:
DTSTART;TZID=US-Eastern:19970905T090000
RRULE:FREQ=MONTHLY;UNTIL=19971224T000000Z;
BYDAY=1FR
==> (1997 9:00 AM EDT)September 5;October 3
(1997 9:00 AM EST)November 7;December 5
Every other month on the 1st and last Sunday of the month for 10
occurrences:
DTSTART;TZID=US-Eastern:19970907T090000
RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;
BYDAY=1SU,-1SU
==> (1997 9:00 AM EDT)September 7,28
(1997 9:00 AM EST)November 2,30
(1998 9:00 AM EST)January 4,25;March 1,29
(1998 9:00 AM EDT)May 3,31
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Monthly on the second to last Monday of the month for 6 months:
DTSTART;TZID=US-Eastern:19970922T090000
RRULE:FREQ=MONTHLY;COUNT=6;BYDAY=-2MO
==> (1997 9:00 AM EDT)September 22;October 20
(1997 9:00 AM EST)November 17;December 22
(1998 9:00 AM EST)January 19;February 16
Monthly on the third to the last day of the month, forever:
DTSTART;TZID=US-Eastern:19970928T090000
RRULE:FREQ=MONTHLY;BYMONTHDAY=-3
==> (1997 9:00 AM EDT)September 28
(1997 9:00 AM EST)October 29;November 28;
December 29(1998 9:00 AM EST)January 29;
February 26
...
Monthly on the 2nd and 15th of the month for 10 occurrences:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=2,15
==> (1997 9:00 AM EDT)September 2,15;October 2,15
(1997 9:00 AM EST)November 2,15;December 2,15
(1998 9:00 AM EST)January 2,15
Monthly on the first and last day of the month for 10 occurrences:
DTSTART;TZID=US-Eastern:19970930T090000
RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=1,-1
==> (1997 9:00 AM EDT)September 30;October 1
(1997 9:00 AM EST)October 31;November 1,30;
December 1,31(1998 9:00 AM EST)January 1,31;
February 1
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Every 18 months on the 10th thru 15th of the month for 10
occurrences:
DTSTART;TZID=US-Eastern:19970910T090000
RRULE:FREQ=MONTHLY;INTERVAL=18;COUNT=10;
BYMONTHDAY=10,11,12,13,14,
15
==> (1997 9:00 AM EDT)September 10,11,12,13,14,15
(1999 9:00 AM EST)March 10,11,12,13
Every Tuesday, every other month:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=MONTHLY;INTERVAL=2;BYDAY=TU
==> (1997 9:00 AM EDT)September 2,9,16,23,30
(1997 9:00 AM EST)November 4,11,18,25
(1998 9:00 AM EST)January 6,13,20,27;
March 3,10,17,24,31
...
Yearly in June and July for 10 occurrences:
DTSTART;TZID=US-Eastern:19970610T090000
RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7
==> (1997 9:00 AM EDT)June 10;July 10
(1998 9:00 AM EDT)June 10;July 10
(1999 9:00 AM EDT)June 10;July 10
(2000 9:00 AM EDT)June 10;July 10
(2001 9:00 AM EDT)June 10;July 10
Note: Since none of the BYDAY, BYMONTHDAY or
BYYEARDAY components are specified, the day is
gotten from DTSTART
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Every other year on January, February, and March
for 10 occurrences:
DTSTART;TZID=US-Eastern:19970310T090000
RRULE:FREQ=YEARLY;INTERVAL=2;COUNT=10;
BYMONTH=1,2,3
==> (1997 9:00 AM EST)March 10
(1999 9:00 AM EST)January 10;February 10;March 10
(2001 9:00 AM EST)January 10;February 10;March 10
(2003 9:00 AM EST)January 10;February 10;March 10
Every 3rd year on the 1st, 100th and 200th day
for 10 occurrences:
DTSTART;TZID=US-Eastern:19970101T090000
RRULE:FREQ=YEARLY;INTERVAL=3;COUNT=10;
BYYEARDAY=1,100,200
==> (1997 9:00 AM EST)January 1
(1997 9:00 AM EDT)April 10;July 19
(2000 9:00 AM EST)January 1
(2000 9:00 AM EDT)April 9;July 18
(2003 9:00 AM EST)January 1
(2003 9:00 AM EDT)April 10;July 19
(2006 9:00 AM EST)January 1
Every 20th Monday of the year, forever:
DTSTART;TZID=US-Eastern:19970519T090000
RRULE:FREQ=YEARLY;BYDAY=20MO
==> (1997 9:00 AM EDT)May 19
(1998 9:00 AM EDT)May 18
(1999 9:00 AM EDT)May 17
...
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Monday of week number 20 (where the default start
of the week is Monday), forever:
DTSTART;TZID=US-Eastern:19970512T090000
RRULE:FREQ=YEARLY;BYWEEKNO=20;BYDAY=MO
==> (1997 9:00 AM EDT)May 12
(1998 9:00 AM EDT)May 11
(1999 9:00 AM EDT)May 17
...
Every Thursday in March, forever:
DTSTART;TZID=US-Eastern:19970313T090000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=TH
==> (1997 9:00 AM EST)March 13,20,27
(1998 9:00 AM EST)March 5,12,19,26
(1999 9:00 AM EST)March 4,11,18,25
...
Every Thursday, but only during June, July, and August,
forever:
DTSTART;TZID=US-Eastern:19970605T090000
RRULE:FREQ=YEARLY;BYDAY=TH;BYMONTH=6,7,8
==> (1997 9:00 AM EDT)June 5,12,19,26;July 3,10,17,24,31;
August 7,14,21,28
(1998 9:00 AM EDT)June 4,11,18,25;July 2,9,16,23,30;
August 6,13,20,27
(1999 9:00 AM EDT)June 3,10,17,24;July 1,8,15,22,29;
August 5,12,19,26
...
Every Friday the 13th, forever:
DTSTART;TZID=US-Eastern:19970902T090000
EXDATE;TZID=US-Eastern:19970902T090000
RRULE:FREQ=MONTHLY;BYDAY=FR;BYMONTHDAY=13
==> (1998 9:00 AM EST)February 13;March 13;
November 13(1999 9:00 AM EDT)August 13
(2000 9:00 AM EDT)October 13
...
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The first Saturday that follows the first Sunday of the month,
forever:
DTSTART;TZID=US-Eastern:19970913T090000
RRULE:FREQ=MONTHLY;BYDAY=SA;
BYMONTHDAY=7,8,9,10,11,12,13
==> (1997 9:00 AM EDT)September 13;October 11
(1997 9:00 AM EST)November 8;December 13
(1998 9:00 AM EST)January 10;February 7;March 7
(1998 9:00 AM EDT)April 11;May 9;June 13...
...
Every four years, the first Tuesday after a Monday in November,
forever (U.S. Presidential Election day):
DTSTART;TZID=US-Eastern:19961105T090000
RRULE:FREQ=YEARLY;INTERVAL=4;BYMONTH=11;
BYDAY=TU;BYMONTHDAY=2,3,4,
5,6,7,8
==> (1996 9:00 AM EST)November 5
(2000 9:00 AM EST)November 7
(2004 9:00 AM EST)November 2
...
The 3rd instance into the month of one of Tuesday, Wednesday or
Thursday, for the next 3 months:
DTSTART;TZID=US-Eastern:19970904T090000
RRULE:FREQ=MONTHLY;COUNT=3;BYDAY=TU,WE,TH;
BYSETPOS=3
==> (1997 9:00 AM EDT)September 4;October 7
(1997 9:00 AM EST)November 6
The 2nd to last weekday of the month:
DTSTART;TZID=US-Eastern:19970929T090000
RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;
BYSETPOS=-2
==> (1997 9:00 AM EDT)September 29
(1997 9:00 AM EST)October 30;November 27;December 30
(1998 9:00 AM EST)January 29;February 26;March 30
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...
Every 3 hours from 9:00 AM to 5:00 PM on a specific day:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=HOURLY;INTERVAL=3;UNTIL=19970902T170000Z
==> (September 2, 1997 EDT)09:00,12:00,15:00
Every 15 minutes for 6 occurrences:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=MINUTELY;INTERVAL=15;COUNT=6
==> (September 2, 1997 EDT)09:00,09:15,09:30,09:45,10:00,10:15
Every hour and a half for 4 occurrences:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=MINUTELY;INTERVAL=90;COUNT=4
==> (September 2, 1997 EDT)09:00,10:30;12:00;13:30
Every 20 minutes from 9:00 AM to 4:40 PM every day:
DTSTART;TZID=US-Eastern:19970902T090000
RRULE:FREQ=DAILY;BYHOUR=9,10,11,12,13,14,15,16;BYMINUTE=0,20,40
or
RRULE:FREQ=MINUTELY;INTERVAL=20;BYHOUR=9,10,11,12,13,14,15,16
==> (September 2, 1997 EDT)9:00,9:20,9:40,10:00,10:20,
... 16:00,16:20,16:40
(September 3, 1997 EDT)9:00,9:20,9:40,10:00,10:20,
...16:00,16:20,16:40
...
An example where the days generated makes a difference because of
WKST:
DTSTART;TZID=US-Eastern:19970805T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=MO
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==> (1997 EDT)Aug 5,10,19,24
changing only WKST from MO to SU, yields different results...
DTSTART;TZID=US-Eastern:19970805T090000
RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=SU
==> (1997 EDT)August 5,17,19,31
8.4. Alarm Component Properties
The following properties specify alarm information in calendar
components.
8.4.1. 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:
action = "ACTION" actionparam ":" actionvalue CRLF
actionparam = *(";" xparam)
actionvalue = "AUDIO" / "DISPLAY" / "EMAIL" / "PROCEDURE"
/ iana-token / x-name
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Example: The following are examples of this property in a "VALARM"
calendar component:
ACTION:AUDIO
ACTION:DISPLAY
ACTION:PROCEDURE
8.4.2. Alarm 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
8.4.3. Alarm 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
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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, time zone
identifier 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 or to-do
that the alarm is associated with. The duration can be explicitly
set to trigger from either the end or the start of the associated
event or to-do with the "RELATED" parameter. A value of START will
set the alarm to trigger off the start of the associated event or
to-do. A value of END will set the alarm to trigger off the end of
the associated event or to-do.
Either a positive or negative duration may be specified for the
"TRIGGER" property. An alarm with a positive duration is triggered
after the associated start or end of the event or to-do. An alarm
with a negative duration is triggered before the associated start or
end of the event or to-do.
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 an
absolute trigger is specified on an alarm for a recurring event or
to-do, then the alarm will only trigger for the specified absolute
date/time, along with any specified repeating instances.
If the trigger is set relative to START, then the "DTSTART" property
MUST be present in the associated "VEVENT" or "VTODO" calendar
component. If an alarm is specified for an event with the trigger
set relative to the END, then the "DTEND" property or the "DSTART"
and "DURATION' properties MUST be present in the associated "VEVENT"
calendar component. If the alarm is specified for a to-do with a
trigger set relative to the END, then either the "DUE" property or
the "DSTART" and "DURATION' properties MUST be present in the
associated "VTODO" calendar component.
Alarms specified in an event or to-do 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:19980205, 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 or
to-do.
TRIGGER:-P15M
A trigger set 5 minutes after the end of the event or to-do.
TRIGGER;RELATED=END:P5M
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A trigger set to an absolute date/time.
TRIGGER;VALUE=DATE-TIME:19980101T050000Z
8.5. Alarm Trigger Relationship
Parameter Name: RELATED
Purpose: To specify the relationship of the alarm trigger with
respect to the start or end of the calendar component.
Description: The parameter can be specified on properties that
specify an alarm trigger with a DURATION value type. The parameter
specifies whether the alarm will trigger relative to the start or end
of the calendar component. The parameter value START will set the
alarm to trigger off the start of the calendar component; the
parameter value END will set the alarm to trigger off the end of the
calendar component. If the parameter is not specified on an
allowable property, then the default is START.
Format Definition: The property parameter is defined by the following
notation:
trigrelparam = "RELATED" "="
("START" ; Trigger off of start
/ "END") ; Trigger off of end
Example:
TRIGGER;RELATED=END:PT5M
Figure 202
8.6. Change Management Component Properties
The following properties specify change management information in
calendar components.
8.6.1. 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
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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", "VTODO"
or "VJOURNAL" 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
Figure 204
8.6.2. 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.
Conformance: This property MUST be included in the "VEVENT", "VTODO",
"VJOURNAL" or "VFREEBUSY" calendar components.
Description: The value MUST be specified in the UTC time format.
This property is also useful to protocols such as [IMIP] that have
inherent latency issues with the delivery of content. This property
will assist in the proper sequencing of messages containing iCalendar
objects.
This property is different than the "CREATED" and "LAST-MODIFIED"
properties. These two properties are used to specify when the
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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
Figure 206
8.6.3. 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 "EVENT", "VTODO",
"VJOURNAL" or "VTIMEZONE" calendar components.
Description: The property value MUST be specified in the UTC time
format.
Format Definition: The property is defined by the following notation:
last-mod = "LAST-MODIFIED" lstparam ":" date-time CRLF
lstparam = *(";" xparam)
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Example: The following is are examples of this property:
LAST-MODIFIED:19960817T133000Z
Figure 208
8.6.4. 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", "VTODO" or
"VJOURNAL" 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 significant revision to the calendar component. When the
"Organizer" makes changes to one of the following properties, the
sequence number MUST be incremented: . "DTSTART" . "DTEND" . "DUE"
. "RDATE" . "RRULE" . "EXDATE" . "EXRULE" . "STATUS"
In addition, changes made by the "Organizer" to other properties can
also force the sequence number to be incremented. The "Organizer"
CUA MUST increment the sequence number when ever it makes changes to
properties in the calendar component that the "Organizer" deems will
jeopardize the validity of the participation status of the
"Attendees". For example, changing the location of a meeting from
one locale to another distant locale could effectively impact the
participation status of the "Attendees".
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
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"RSVP" parameter on the "ATTENDEE" property is used by the
"Organizer" to indicate that a response from the "Attendees" is
requested.
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
8.7. Miscellaneous Component Properties
The following properties specify information about a number of
miscellaneous features of calendar components.
8.7.1. RSVP Expectation
Parameter Name: RSVP
Purpose: To specify whether there is an expectation of a favor of a
reply from the calendar user specified by the property value.
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter identifies the expectation of
a reply from the calendar user specified by the property value. This
parameter is used by the "Organizer" to request a participation
status reply from an "Attendee" of a group scheduled event or to-do.
If not specified on a property that allows this parameter, the
default value is FALSE.
Format Definition: The property parameter is defined by the following
notation:
rsvpparam = "RSVP" "=" ("TRUE" / "FALSE")
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; Default is FALSE
Example:
ATTENDEE;RSVP=TRUE:MAILTO:jsmith@host.com
Figure 213
8.7.2. Language
Parameter Name: LANGUAGE
Purpose: To specify the language for text values in a property or
property parameter.
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 [RFC 1766].
For transport in a MIME entity, the Content-Language header field can
be used to set the default language for the entire body part.
Otherwise, no default language is assumed.
Format Definition: The property parameter is defined by the following
notation:
languageparam = "LANGUAGE" "=" language
language = Project XYZ Review Meeting will include the following
agenda items: