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RFC 2445 - Internet Calendaring and Scheduling Core Object Specification (iCalendar)
Abstract
There is a clear need to provide and deploy interoperable calendaring
and scheduling services for the Internet. Current group scheduling
and Personal Information Management (PIM) products are being extended
for use across the Internet, today, in proprietary ways. This memo
has been defined to provide the definition of a common format for
openly exchanging calendaring and scheduling information across the
Internet.
This memo is formatted as a registration for a MIME media type per
[RFC 2048]. However, the format in this memo is equally applicable
for use outside of a MIME message content type.
The proposed media type value is 'text/calendar'. This string would
label a media type containing calendaring and scheduling information
encoded as text characters formatted in a manner outlined below.
This MIME media type provides a standard content type for capturing
calendar event, to-do and journal entry information. It also can be
used to convey free/busy time information. The content type is
suitable as a MIME message entity that can be transferred over MIME
based email systems, using HTTP or some other Internet transport. In
addition, the content type is useful as an object for interactions
between desktop applications using the operating system clipboard,
drag/drop or file systems capabilities.
This memo is based on the earlier work of the vCalendar specification
for the exchange of personal calendaring and scheduling information.
In order to avoid confusion with this referenced work, this memo is
to be known as the iCalendar specification.
This memo defines the format for specifying iCalendar object methods.
An iCalendar object method is a set of usage constraints for the
iCalendar object. For example, these methods might define scheduling
messages that request an event be scheduled, reply to an event
request, send a cancellation notice for an event, modify or replace
the definition of an event, provide a counter proposal for an
original event request, delegate an event request to another
individual, request free or busy time, reply to a free or busy time
request, or provide similar scheduling messages for a to-do or
journal entry calendar component. The iCalendar Transport-indendent
Interoperability Protocol (iTIP) defined in [ITIP] is one such
scheduling protocol.
Table of Contents
1 Introduction.....................................................5
2 Basic Grammar and Conventions....................................6
2.1 Formatting Conventions .......................................7
2.2 Related Memos ................................................8
2.3 International Considerations .................................8
3 Registration Information.........................................8
3.1 Content Type .................................................8
3.2 Parameters ...................................................9
3.3 Content Header Fields .......................................10
3.4 Encoding Considerations .....................................10
3.5 Security Considerations .....................................10
3.6 Interoperability Considerations .............................11
3.7 Applications Which Use This Media Type ......................11
3.8 Additional Information ......................................11
3.9 Magic Numbers ...............................................11
3.10 File Extensions ............................................11
3.11 Contact for Further Information: ...........................12
3.12 Intended Usage .............................................12
3.13 Authors/Change Controllers .................................12
4 iCalendar Object Specification..................................13
4.1 Content Lines ...............................................13
4.1.1 List and Field Separators ................................16
4.1.2 Multiple Values ..........................................16
4.1.3 Binary Content ...........................................16
4.1.4 Character Set ............................................17
4.2 Property Parameters .........................................17
4.2.1 Alternate Text Representation ............................18
4.2.2 Common Name ..............................................19
4.2.3 Calendar User Type .......................................20
4.2.4 Delegators ...............................................20
4.2.5 Delegatees ...............................................21
4.2.6 Directory Entry Reference ................................21
4.2.7 Inline Encoding ..........................................22
4.2.8 Format Type ..............................................23
4.2.9 Free/Busy Time Type ......................................23
4.2.10 Language ................................................24
4.2.11 Group or List Membership ................................25
4.2.12 Participation Status ....................................25
4.2.13 Recurrence Identifier Range .............................27
4.2.14 Alarm Trigger Relationship ..............................27
4.2.15 Relationship Type .......................................28
4.2.16 Participation Role ......................................29
4.2.17 RSVP Expectation ........................................29
4.2.18 Sent By .................................................30
4.2.19 Time Zone Identifier ....................................30
4.2.20 Value Data Types ........................................32
4.3 Property Value Data Types ...................................32
4.3.1 Binary ...................................................33
4.3.2 Boolean ..................................................33
4.3.3 Calendar User Address ....................................34
4.3.4 Date .....................................................34
4.3.5 Date-Time ................................................35
4.3.6 Duration .................................................37
4.3.7 Float ....................................................38
4.3.8 Integer ..................................................38
4.3.9 Period of Time ...........................................39
4.3.10 Recurrence Rule .........................................40
4.3.11 Text ....................................................45
4.3.12 Time ....................................................47
4.3.13 URI .....................................................49
4.3.14 UTC Offset ..............................................49
4.4 iCalendar Object ............................................50
4.5 Property ....................................................51
4.6 Calendar Components .........................................51
4.6.1 Event Component ..........................................52
4.6.2 To-do Component ..........................................55
4.6.3 Journal Component ........................................56
4.6.4 Free/Busy Component ......................................58
4.6.5 Time Zone Component ......................................60
4.6.6 Alarm Component ..........................................67
4.7 Calendar Properties .........................................73
4.7.1 Calendar Scale ...........................................73
4.7.2 Method ...................................................74
4.7.3 Product Identifier .......................................75
4.7.4 Version ..................................................76
4.8 Component Properties ........................................77
4.8.1 Descriptive Component Properties .........................77
4.8.1.1 Attachment ...........................................77
4.8.1.2 Categories ...........................................78
4.8.1.3 Classification .......................................79
4.8.1.4 Comment ..............................................80
4.8.1.5 Description ..........................................81
4.8.1.6 Geographic Position ..................................82
4.8.1.7 Location .............................................84
4.8.1.8 Percent Complete .....................................85
4.8.1.9 Priority .............................................85
4.8.1.10 Resources ...........................................87
4.8.1.11 Status ..............................................88
4.8.1.12 Summary .............................................89
4.8.2 Date and Time Component Properties .......................90
4.8.2.1 Date/Time Completed ..................................90
4.8.2.2 Date/Time End ........................................91
4.8.2.3 Date/Time Due ........................................92
4.8.2.4 Date/Time Start ......................................93
4.8.2.5 Duration .............................................94
4.8.2.6 Free/Busy Time .......................................95
4.8.2.7 Time Transparency ....................................96
4.8.3 Time Zone Component Properties ...........................97
4.8.3.1 Time Zone Identifier .................................97
4.8.3.2 Time Zone Name .......................................98
4.8.3.3 Time Zone Offset From ................................99
4.8.3.4 Time Zone Offset To .................................100
4.8.3.5 Time Zone URL .......................................101
4.8.4 Relationship Component Properties .......................102
4.8.4.1 Attendee ............................................102
4.8.4.2 Contact .............................................104
4.8.4.3 Organizer ...........................................106
4.8.4.4 Recurrence ID .......................................107
4.8.4.5 Related To ..........................................109
4.8.4.6 Uniform Resource Locator ............................110
4.8.4.7 Unique Identifier ...................................111
4.8.5 Recurrence Component Properties .........................112
4.8.5.1 Exception Date/Times ................................112
4.8.5.2 Exception Rule ......................................114
4.8.5.3 Recurrence Date/Times ...............................115
4.8.5.4 Recurrence Rule .....................................117
4.8.6 Alarm Component Properties ..............................126
4.8.6.1 Action ..............................................126
4.8.6.2 Repeat Count ........................................126
4.8.6.3 Trigger .............................................127
4.8.7 Change Management Component Properties ..................129
4.8.7.1 Date/Time Created ...................................129
4.8.7.2 Date/Time Stamp .....................................130
4.8.7.3 Last Modified .......................................131
4.8.7.4 Sequence Number .....................................131
4.8.8 Miscellaneous Component Properties ......................133
4.8.8.1 Non-standard Properties .............................133
4.8.8.2 Request Status ......................................134
5 iCalendar Object Examples......................................136
6 Recommended Practices..........................................140
7 Registration of Content Type Elements..........................141
7.1 Registration of New and Modified iCalendar Object Methods ..141
7.2 Registration of New Properties .............................141
7.2.1 Define the property .....................................142
7.2.2 Post the Property definition ............................143
7.2.3 Allow a comment period ..................................143
7.2.4 Submit the property for approval ........................143
7.3 Property Change Control ....................................143
8 References.....................................................144
9 Acknowledgments................................................145
10 Authors' and Chairs' Addresses................................146
11 Full Copyright Statement......................................148
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 content type
for exchanging electronic calendaring and scheduling information. The
Internet Calendaring and Scheduling Core Object Specification, or
iCalendar, allows for the capture and exchange of information
normally stored within a calendaring and scheduling application; such
as a Personal Information Manager (PIM) or a Group Scheduling
product.
The 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. Such a scheduling protocol is
defined in the iCalendar Transport-independent Interoperability
Protocol (iTIP) defined in [ITIP].
The memo also includes a formal grammar for the content type based on
the Internet ABNF defined in [RFC 2234]. This ABNF is required for
the implementation of parsers and to serve as the definitive
reference when ambiguities or questions arise in interpreting the
descriptive prose definition of the memo.
2 Basic Grammar and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY" and
"OPTIONAL" in this document are to be interoperated as described in
[RFC 2119].
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].
Readers intending on implementing this format defined in this memo
should be familiar with this notation in order to properly interpret
the specifications of this memo.
All numeric and hexadecimal values used in this memo are given in
decimal notation.
All names of properties, property parameters, enumerated property
values and property parameter values are case-insensitive. However,
all other property values are case-sensitive, unless otherwise
stated.
Note: All indented editorial notes, such as this one, are
intended to provide the reader with additional information. The
information is not essential to the building of an
implementation conformant with this memo. The information is
provided to highlight a particular feature or characteristic of
the memo.
The format for the iCalendar object is based on the syntax of the
[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.
2.1 Formatting Conventions
The mechanisms defined in this memo are defined in prose. Many of the
terms used to describe these have common usage that is different than
the standards usage of this memo. In order to reference within this
memo elements of the calendaring and scheduling model, core object
(this memo) or interoperability protocol [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.
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.
2.2 Related Memos
Implementers will need to be familiar with several other memos that,
along with this memo, form a framework for Internet calendaring and
scheduling standards. This memo, [ICAL], specifies a core
specification of objects, data types, properties and property
parameters.
[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.
2.3 International Considerations
In the rest of this document, descriptions of characters are of the
form "character name (codepoint)", where "codepoint" is from the US-
ASCII character set. The "character name" is the authoritative
description; (codepoint) is a reference to that character in US-ASCII
or US-ASCII compatible sets (for example the ISO-8859-x family, UTF-
8, ISO-2022-xx, KOI8-R). If a non-US-ASCII compatible character set
is used, appropriate code-point from that character set MUST be
chosen instead. Use of non-US-ASCII-compatible character sets is NOT
recommended.
3 Registration Information
The Calendaring and Scheduling Core Object Specification is intended
for use as a MIME content type. However, the implementation of the
memo is in no way limited solely as a MIME content type.
3.1 Content Type
The following text is intended to register this memo as the MIME
content type "text/calendar".
To: ietf-types@uninett.no
Subject: Registration of MIME content type text/calendar.
MIME media type name: text
MIME subtype name: calendar
3.2 Parameters
Required parameters: none
Optional parameters: charset, method, component and optinfo
The "charset" parameter is defined in [RFC 2046] for other body
parts. It is used to identify the default character set used within
the body part.
The "method" parameter is used to convey the iCalendar object method
or transaction semantics for the calendaring and scheduling
information. It also is an identifier for the restricted set of
properties and values that the iCalendar object consists of. The
parameter is to be used as a guide for applications interpreting the
information contained within the body part. It SHOULD NOT be used to
exclude or require particular pieces of information unless the
identified method definition specifically calls for this behavior.
Unless specifically forbidden by a particular method definition, a
text/calendar content type can contain any set of properties
permitted by the Calendaring and Scheduling Core Object
Specification. The "method" parameter MUST be the same value as that
specified in the "METHOD" component property in the iCalendar object.
If one is present, the other MUST also be present.
The value for the "method" parameter is defined as follows:
method = 1*(ALPHA / DIGIT / "-")
; IANA registered iCalendar object method
The "component" parameter conveys the type of iCalendar calendar
component within the body part. If the iCalendar object contains more
than one calendar component type, then multiple component parameters
MUST be specified.
The value for the "component" parameter is defined as follows:
component = ("VEVENT" / "VTODO" / "VJOURNAL" / "VFREEBUSY"
/ "VTIMEZONE" / x-name / iana-token)
The "optinfo" parameter conveys optional information about the
iCalendar object within the body part. This parameter can only
specify semantics already specified by the iCalendar object and that
can be otherwise determined by parsing the body part. In addition,
the optional information specified by this parameter MUST be
consistent with that information specified by the iCalendar object.
For example, it can be used to convey the "Attendee" response status
to a meeting request. The parameter value consists of a string value.
The parameter can be specified multiple times.
This parameter MAY only specify semantics already specified by the
iCalendar object and that can be otherwise determined by parsing the
body part.
The value for the "optinfo" parameter is defined as follows:
optinfo = infovalue / qinfovalue
infovalue = iana-token / x-name
qinfovalue = DQUOTE (infovalue) DQUOTE
3.3 Content Header Fields
Optional content header fields: Any header fields defined by [RFC
2045].
3.4 Encoding Considerations
This MIME content type can contain 8bit characters, so the use of
quoted-printable or BASE64 MIME content-transfer-encodings might be
necessary when iCalendar objects are transferred across protocols
restricted to the 7bit repertoire. Note that a text valued property
in the content entity can also have content encoding of special
characters using a BACKSLASH character (US-ASCII decimal 92)
escapement technique. This means that content values can end up
encoded twice.
3.5 Security Considerations
SPOOFING - - In this memo, the "Organizer" is the only person
authorized to make changes to an existing "VEVENT", "VTODO",
"VJOURNAL" calendar component and redistribute the updates to the
"Attendees". An iCalendar object that maliciously changes or cancels
an existing "VEVENT", "VTODO" or "VJOURNAL" or "VFREEBUSY" calendar
component might be constructed by someone other than the "Organizer"
and sent to the "Attendees". In addition in this memo, other than the
"Organizer", an "Attendee" of a "VEVENT", "VTODO", "VJOURNAL"
calendar component is the only other person authorized to update any
parameter associated with their "ATTENDEE" property and send it to
the "Organizer". An iCalendar object that maliciously changes the
"ATTENDEE" parameters can be constructed by someone other than the
real "Attendee" and sent to the "Organizer".
PROCEDURAL ALARMS - - An iCalendar object can be created that
contains a "VEVENT" and "VTODO" calendar component with "VALARM"
calendar components. The "VALARM" calendar component can be of type
PROCEDURE and can have an attachment containing some sort of
executable program. Implementations that incorporate these types of
alarms are subject to any virus or malicious attack that might occur
as a result of executing the attachment.
ATTACHMENTS - - An iCalendar object can include references to Uniform
Resource Locators that can be programmed resources.
Implementers and users of this memo should be aware of the network
security implications of accepting and parsing such information. In
addition, the security considerations observed by implementations of
electronic mail systems should be followed for this memo.
3.6 Interoperability Considerations
This MIME content type is intended to define a common format for
conveying calendaring and scheduling information between different
systems. It is heavily based on the earlier [VCAL] industry
specification.
3.7 Applications Which Use This Media Type
This content-type is designed for widespread use by Internet
calendaring and scheduling applications. In addition, applications in
the workflow and document management area might find this content-
type applicable. The [ITIP] and [IMIP] Internet protocols directly
use this content-type also. Future work on an Internet calendar
access protocol will utilize this content-type too.
3.8 Additional Information
This memo defines this content-type.
3.9 Magic Numbers
None.
3.10 File Extensions
The file extension of "ics" is to be used to designate a file
containing (an arbitrary set of) calendaring and scheduling
information consistent with this MIME content type.
The file extension of "ifb" is to be used to designate a file
containing free or busy time information consistent with this MIME
content type.
Macintosh file type codes: The file type code of "iCal" is to be used
in Apple MacIntosh operating system environments to designate a file
containing calendaring and scheduling information consistent with
this MIME media type.
The file type code of "iFBf" is to be used in Apple MacIntosh
operating system environments to designate a file containing free or
busy time information consistent with this MIME media type.
3.11 Contact for Further Information:
Frank Dawson
6544 Battleford Drive
Raleigh, NC 27613-3502
919-676-9515 (Telephone)
919-676-9564 (Data/Facsimile)
Frank_Dawson@Lotus.com (Internet Mail)
Derik Stenerson
One Microsoft Way
Redmond, WA 98052-6399
425-936-5522 (Telephone)
425-936-7329 (Facsimile)
deriks@microsoft.com (Internet Mail)
3.12 Intended Usage
COMMON
3.13 Authors/Change Controllers
Frank Dawson
6544 Battleford Drive
Raleigh, NC 27613-3502
919-676-9515 (Telephone)
919-676-9564 (Data/Facsimile)
Frank_Dawson@Lotus.com (Internet Mail)
Derik Stenerson
One Microsoft Way
Redmond, WA 98052-6399
425-936-5522 (Telephone)
425-936-7329 (Facsimile)
deriks@microsoft.com (Internet Mail)
4 iCalendar Object Specification
The following sections define the details of a Calendaring and
Scheduling Core Object Specification. This information is intended to
be an integral part of the MIME content type registration. In
addition, this information can be used independent of such content
registration. In particular, this memo has direct applicability for
use as a calendaring and scheduling exchange format in file-, memory-
or network-based transport mechanisms.
4.1 Content Lines
The iCalendar object is organized into individual lines of text,
called content lines. Content lines are delimited by a line break,
which is a CRLF sequence (US-ASCII decimal 13, followed by US-ASCII
decimal 10).
Lines of text SHOULD NOT be longer than 75 octets, excluding the line
break. Long content lines SHOULD be split into a multiple line
representations using a line "folding" technique. That is, a long
line can be split between any two characters by inserting a CRLF
immediately followed by a single linear white space character (i.e.,
SPACE, US-ASCII decimal 32 or HTAB, US-ASCII decimal 9). Any sequence
of CRLF followed immediately by a single linear white space character
is ignored (i.e., removed) when processing the content type.
For example the line:
DESCRIPTION:This is a long description that exists on a long line.
Can be represented as:
DESCRIPTION:This is a lo
ng description
that exists on a long line.
The process of moving from this folded multiple line representation
to its single line representation is called "unfolding". Unfolding is
accomplished by removing the CRLF character and the linear white
space character that immediately follows.
When parsing a content line, folded lines MUST first be unfolded
according to the unfolding procedure described above. When generating
a content line, lines longer than 75 octets SHOULD be folded
according to the folding procedure described above.
The content information associated with an iCalendar object is
formatted using a syntax similar to that defined by [RFC 2425]. That
is, the content information consists of CRLF-separated content lines.
The following notation defines the lines of content in an iCalendar
object:
contentline = name *(";" param ) ":" value CRLF
; This ABNF is just a general definition for an initial parsing
; of the content line into its property name, parameter list,
; and value string
; When parsing a content line, folded lines MUST first
; be unfolded according to the unfolding procedure
; described above. When generating a content line, lines
; longer than 75 octets SHOULD be folded according to
; the folding procedure described above.
name = x-name / iana-token
iana-token = 1*(ALPHA / DIGIT / "-")
; iCalendar identifier registered with IANA
x-name = "X-" [vendorid "-"] 1*(ALPHA / DIGIT / "-")
; Reservered for experimental use. Not intended for use in
; released products.
vendorid = 3*(ALPHA / DIGIT) ;Vendor identification
param = param-name "=" param-value
*("," param-value)
; Each property defines the specific ABNF for the parameters
; allowed on the property. Refer to specific properties for
; precise parameter ABNF.
param-name = iana-token / x-token
param-value = paramtext / quoted-string
paramtext = *SAFE-CHAR
value = *VALUE-CHAR
quoted-string = DQUOTE *QSAFE-CHAR DQUOTE
NON-US-ASCII = %x80-F8
; Use restricted by charset parameter
; on outer MIME object (UTF-8 preferred)
QSAFE-CHAR = WSP / %x21 / %x23-7E / NON-US-ASCII
; Any character except CTLs and DQUOTE
SAFE-CHAR = WSP / %x21 / %x23-2B / %x2D-39 / %x3C-7E
/ NON-US-ASCII
; Any character except CTLs, DQUOTE, ";", ":", ","
VALUE-CHAR = WSP / %x21-7E / NON-US-ASCII
; Any textual character
CR = %x0D
; carriage return
LF = %x0A
; line feed
CRLF = CR LF
; Internet standard newline
CTL = %x00-08 / %x0A-1F / %x7F
; Controls
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
DIGIT = %x30-39
; 0-9
DQUOTE = %x22
; Quotation Mark
WSP = SPACE / HTAB
SPACE = %x20
HTAB = %x09
The property value component of a content line has a format that is
property specific. Refer to the section describing each property for
a definition of this format.
All names of properties, property parameters, enumerated property
values and property parameter values are case-insensitive. However,
all other property values are case-sensitive, unless otherwise
stated.
4.1.1 List and Field Separators
Some properties and parameters allow a list of values. Values in a
list of values MUST be separated by a COMMA character (US-ASCII
decimal 44). There is no significance to the order of values in a
list. For those parameter values (such as those that specify URI
values) that are specified in quoted-strings, the individual quoted-
strings are separated by a COMMA character (US-ASCII decimal 44).
Some property values are defined in terms of multiple parts. These
structured property values MUST have their value parts separated by a
SEMICOLON character (US-ASCII decimal 59).
Some properties allow a list of parameters. Each property parameter
in a list of property parameters MUST be separated by a SEMICOLON
character (US-ASCII decimal 59).
Property parameters with values containing a COLON, a SEMICOLON or a
COMMA character MUST be placed in quoted text.
For example, in the following properties a SEMICOLON is used to
separate property parameters from each other, and a COMMA is used to
separate property values in a value list.
ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:MAILTO:
jsmith@host.com
RDATE;VALUE=DATE:19970304,19970504,19970704,19970904
4.1.2 Multiple Values
Some properties defined in the iCalendar object can have multiple
values. The general rule for encoding multi-valued items is to simply
create a new content line for each value, including the property
name. However, it should be noted that some properties support
encoding multiple values in a single property by separating the
values with a COMMA character (US-ASCII decimal 44). Individual
property definitions should be consulted for determining whether a
specific property allows multiple values and in which of these two
forms.
4.1.3 Binary Content
Binary content information in an iCalendar object SHOULD be
referenced using a URI within a property value. That is the binary
content information SHOULD be placed in an external MIME entity that
can be referenced by a URI from within the iCalendar object. In
applications where this is not feasible, binary content information
can be included within an iCalendar object, but only after first
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...>
4.1.4 Character Set
There is not a property parameter to declare the character set used
in a property value. The default character set for an iCalendar
object is UTF-8 as defined in [RFC 2279].
The "charset" Content-Type parameter can be used in MIME transports
to specify any other IANA registered character set.
4.2 Property Parameters
A property can have attributes associated with it. These "property
parameters" contain meta-information about the property or the
property value. Property parameters are provided to specify such
information as the location of an alternate text representation for a
property value, the language of a text property value, the data type
of the property value and other attributes.
Property parameter values that contain the COLON (US-ASCII decimal
58), SEMICOLON (US-ASCII decimal 59) or COMMA (US-ASCII decimal 44)
character separators MUST be specified as quoted-string text values.
Property parameter values MUST NOT contain the DOUBLE-QUOTE (US-ASCII
decimal 22) character. The DOUBLE-QUOTE (US-ASCII decimal 22)
character is used as a delimiter for parameter values that contain
restricted characters or URI text. For example:
DESCRIPTION;ALTREP="http://www.wiz.org":The Fall'98 Wild Wizards
Conference - - Las Vegas, NV, USA
Property parameter values that are not in quoted strings are case
insensitive.
The general property parameters defined by this memo are defined by
the following notation:
parameter = altrepparam ; Alternate text representation
/ cnparam ; Common name
/ cutypeparam ; Calendar user type
/ delfromparam ; Delegator
/ deltoparam ; Delegatee
/ dirparam ; Directory entry
/ encodingparam ; Inline encoding
/ fmttypeparam ; Format type
/ fbtypeparam ; Free/busy time type
/ languageparam ; Language for text
/ memberparam ; Group or list membership
/ partstatparam ; Participation status
/ rangeparam ; Recurrence identifier range
/ trigrelparam ; Alarm trigger relationship
/ reltypeparam ; Relationship type
/ roleparam ; Participation role
/ rsvpparam ; RSVP expectation
/ sentbyparam ; Sent by
/ tzidparam ; Reference to time zone object
/ valuetypeparam ; Property value data type
/ ianaparam
; Some other IANA registered iCalendar parameter.
/ xparam
; A non-standard, experimental parameter.
ianaparam = iana-token "=" param-value *("," param-value)
xparam =x-name "=" param-value *("," param-value)
4.2.1 Alternate Text Representation
Parameter Name: ALTREP
Purpose: To specify an alternate text representation for the property
value.
Format Definition: The property parameter is defined by the following
notation:
altrepparam = "ALTREP" "=" DQUOTE uri DQUOTE
Description: The parameter specifies a URI that points to an
alternate representation for a textual property value. A property
specifying this parameter MUST also include a value that reflects the
default representation of the text value. The individual URI
parameter values MUST each be specified in a quoted-string.
Example:
DESCRIPTION;ALTREP="CID:":Project
XYZ Review Meeting will include the following agenda items: (a)
Market Overview, (b) Finances, (c) Project Management
The "ALTREP" property parameter value might point to a "text/html"
content portion.
Content-Type:text/html
Content-Id:
Project XYZ Review Meeting will include the following
agenda items: - Market
Overview
- Finances
- Project Management
4.2.2 Common Name
Parameter Name: CN
Purpose: To specify the common name to be associated with the
calendar user specified by the property.
Format Definition: The property parameter is defined by the following
notation:
cnparam = "CN" "=" param-value
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter specifies the common name to be
associated with the calendar user specified by the property. The
parameter value is text. The parameter value can be used for display
text to be associated with the calendar address specified by the
property.
Example:
ORGANIZER;CN="John Smith":MAILTO:jsmith@host.com
4.2.3 Calendar User Type
Parameter Name: CUTYPE
Purpose: To specify the type of calendar user specified by the
property.
Format Definition: The property parameter is defined by the following
notation:
cutypeparam = "CUTYPE" "="
("INDIVIDUAL" ; An individual
/ "GROUP" ; A group of individuals
/ "RESOURCE" ; A physical resource
/ "ROOM" ; A room resource
/ "UNKNOWN" ; Otherwise not known
/ x-name ; Experimental type
/ iana-token) ; Other IANA registered
; type
; Default is INDIVIDUAL
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter identifies the type of calendar
user specified by the property. If not specified on a property that
allows this parameter, the default is INDIVIDUAL.
Example:
ATTENDEE;CUTYPE=GROUP:MAILTO:ietf-calsch@imc.org
4.2.4 Delegators
Parameter Name: DELEGATED-FROM
Purpose: To specify the calendar users that have delegated their
participation to the calendar user specified by the property.
Format Definition: The property parameter is defined by the following
notation:
delfromparam = "DELEGATED-FROM" "=" DQUOTE cal-address DQUOTE
*("," DQUOTE cal-address DQUOTE)
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.
Example:
ATTENDEE;DELEGATED-FROM="MAILTO:jsmith@host.com":MAILTO:
jdoe@host.com
4.2.5 Delegatees
Parameter Name: DELEGATED-TO
Purpose: To specify the calendar users to whom the calendar user
specified by the property has delegated participation.
Format Definition: The property parameter is defined by the following
notation:
deltoparam = "DELEGATED-TO" "=" DQUOTE cal-address DQUOTE
*("," DQUOTE cal-address DQUOTE)
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 calendar
address parameter values MUST each be specified in a quoted-string.
Example:
ATTENDEE;DELEGATED-TO="MAILTO:jdoe@host.com","MAILTO:jqpublic@
host.com":MAILTO:jsmith@host.com
4.2.6 Directory Entry Reference
Parameter Name: DIR
Purpose: To specify reference to a directory entry associated with
the calendar user specified by the property.
Format Definition: The property parameter is defined by the following
notation:
dirparam = "DIR" "=" DQUOTE uri DQUOTE
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter specifies a reference to the
directory entry associated with the calendar user specified by the
property. The parameter value is a URI. The individual URI parameter
values MUST each be specified in a quoted-string.
Example:
ORGANIZER;DIR="ldap://host.com:6666/o=eDABC%20Industries,c=3DUS??
(cn=3DBJim%20Dolittle)":MAILTO:jimdo@host1.com
4.2.7 Inline Encoding
Parameter Name: ENCODING
Purpose: To specify an alternate inline encoding for the property
value.
Format Definition: The property parameter is defined by the following
notation:
encodingparam = "ENCODING" "="
("8BIT"
; "8bit" text encoding is defined in [RFC 2045]
/ "BASE64"
; "BASE64" binary encoding format is defined in [RFC 2045]
/ iana-token
; Some other IANA registered iCalendar encoding type
/ x-name)
; A non-standard, experimental encoding type
Description: The property parameter identifies the inline encoding
used in a property value. The default encoding is "8BIT",
corresponding to a property value consisting of text. The "BASE64"
encoding type corresponds to a property value encoded using the
"BASE64" encoding defined in [RFC 2045].
If the value type parameter is ";VALUE=BINARY", then the inline
encoding parameter MUST be specified with the value
";ENCODING=BASE64".
Example:
ATTACH;FMTYPE=IMAGE/JPEG;ENCODING=BASE64;VALUE=BINARY:MIICajC
CAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDA
qBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRw
<...remainder of "BASE64" encoded binary data...>
4.2.8 Format Type
Parameter Name: FMTTYPE
Purpose: To specify the content type of a referenced object.
Format Definition: The property parameter is defined by the following
notation:
fmttypeparam = "FMTTYPE" "=" iana-token
; A IANA registered content type
/ x-name
; A non-standard content type
Description: This parameter can be specified on properties that are
used to reference an object. The parameter specifies the content type
of the referenced object. For example, on the "ATTACH" property, a
FTP type URI value does not, by itself, necessarily convey the type
of content associated with the resource. The parameter value MUST be
the TEXT for either an IANA registered content type or a non-standard
content type.
Example:
ATTACH;FMTTYPE=application/binary:ftp://domain.com/pub/docs/
agenda.doc
4.2.9 Free/Busy Time Type
Parameter Name: FBTYPE
Purpose: To specify the free or busy time type.
Format Definition: The property parameter is defined by the following
notation:
fbtypeparam = "FBTYPE" "=" ("FREE" / "BUSY"
/ "BUSY-UNAVAILABLE" / "BUSY-TENTATIVE"
/ x-name
; Some experimental iCalendar data type.
/ iana-token)
; Some other IANA registered iCalendar data type.
Description: The parameter specifies the free or busy time type. The
value FREE indicates that the time interval is free for scheduling.
The value BUSY indicates that the time interval is busy because one
or more events have been scheduled for that interval. The value
BUSY-UNAVAILABLE indicates that the time interval is busy and that
the interval can not be scheduled. The value BUSY-TENTATIVE indicates
that the time interval is busy because one or more events have been
tentatively scheduled for that interval. If not specified on a
property that allows this parameter, the default is BUSY.
Example: The following is an example of this parameter on a FREEBUSY
property.
FREEBUSY;FBTYPE=BUSY:19980415T133000Z/19980415T170000Z
4.2.10 Language
Parameter Name: LANGUAGE
Purpose: To specify the language for text values in a property or
property parameter.
Format Definition: The property parameter is defined by the following
notation:
languageparam = "LANGUAGE" "=" language
language =
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.
Example:
SUMMARY;LANGUAGE=us-EN:Company Holiday Party
LOCATION;LANGUAGE=en:Germany
LOCATION;LANGUAGE=no:Tyskland
The following example makes use of the Quoted-Printable encoding in
order to represent non-ASCII characters.
LOCATION;LANGUAGE=da:K=F8benhavn
LOCATION;LANGUAGE=en:Copenhagen
4.2.11 Group or List Membership
Parameter Name: MEMBER
Purpose: To specify the group or list membership of the calendar user
specified by the property.
Format Definition: The property parameter is defined by the following
notation:
memberparam = "MEMBER" "=" DQUOTE cal-address DQUOTE
*("," DQUOTE cal-address DQUOTE)
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter identifies the groups or list
membership for the calendar user specified by the property. The
parameter value either a single calendar address in a quoted-string
or a COMMA character (US-ASCII decimal 44) list of calendar
addresses, each in a quoted-string. The individual calendar address
parameter values MUST each be specified in a quoted-string.
Example:
ATTENDEE;MEMBER="MAILTO:ietf-calsch@imc.org":MAILTO:jsmith@host.com
ATTENDEE;MEMBER="MAILTO:projectA@host.com","MAILTO:projectB@host.
com":MAILTO:janedoe@host.com
4.2.12 Participation Status
Parameter Name: PARTSTAT
Purpose: To specify the participation status for the calendar user
specified by the property.
Format Definition: The property parameter is defined by the following
notation:
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
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.
Example:
ATTENDEE;PARTSTAT=DECLINED:MAILTO:jsmith@host.com
4.2.13 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.
Format Definition: The property parameter is defined by the following
notation:
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
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
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.
Example:
RECURRENCE-ID;RANGE=THISANDPRIOR:19980401T133000Z
4.2.14 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.
Format Definition: The property parameter is defined by the following
notation:
trigrelparam = "RELATED" "="
("START" ; Trigger off of start
/ "END") ; Trigger off of end
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.
Example:
TRIGGER;RELATED=END:PT5M
4.2.15 Relationship Type
Parameter Name: RELTYPE
Purpose: To specify the type of hierarchical relationship associated
with the calendar component specified by the property.
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
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.
Example:
RELATED-TO;RELTYPE=SIBLING:<19960401-080045-4000F192713@host.com>
4.2.16 Participation Role
Parameter Name: ROLE
Purpose: To specify the participation role for the calendar user
specified by the property.
Format Definition: The property parameter is defined by the following
notation:
roleparam = "ROLE" "="
("CHAIR" ; Indicates chair of the
; calendar entity
/ "REQ-PARTICIPANT" ; Indicates a participant whose
; participation is required
/ "OPT-PARTICIPANT" ; Indicates a participant whose
; participation is optional
/ "NON-PARTICIPANT" ; Indicates a participant who is
; copied for information
; purposes only
/ x-name ; Experimental role
/ iana-token) ; Other IANA role
; Default is REQ-PARTICIPANT
Description: This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter specifies the participation
role for the calendar user specified by the property in the group
schedule calendar component. If not specified on a property that
allows this parameter, the default value is REQ-PARTICIPANT.
Example:
ATTENDEE;ROLE=CHAIR:MAILTO:mrbig@host.com
4.2.17 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.
Format Definition: The property parameter is defined by the following
notation:
rsvpparam = "RSVP" "=" ("TRUE" / "FALSE")
; Default is FALSE
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.
Example:
ATTENDEE;RSVP=TRUE:MAILTO:jsmith@host.com
4.2.18 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.
Format Definition: The property parameter is defined by the following
notation:
sentbyparam = "SENT-BY" "=" DQUOTE cal-address DQUOTE
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.
Example:
ORGANIZER;SENT-BY:"MAILTO:sray@host.com":MAILTO:jsmith@host.com
4.2.19 Time Zone Identifier
Parameter Name: TZID
Purpose: To specify the identifier for the time zone definition for a
time component in the property value.
Format Definition: This property parameter is defined by the
following notation:
tzidparam = "TZID" "=" [tzidprefix] paramtext CRLF
tzidprefix = "/"
Description: The parameter MUST be specified on the "DTSTART",
"DTEND", "DUE", "EXDATE" and "RDATE" properties when either a DATE-
TIME or TIME value type is specified and when the value is not either
a UTC or a "floating" time. Refer to the DATE-TIME or TIME value type
definition for a description of UTC and "floating time" formats. This
property parameter specifies a text value which uniquely identifies
the "VTIMEZONE" calendar component to be used when evaluating the
time portion of the property. The value of the TZID property
parameter will be equal to the value of the TZID property for the
matching time zone definition. An individual "VTIMEZONE" calendar
component MUST be specified for each unique "TZID" parameter value
specified in the iCalendar object.
The parameter MUST be specified on properties with a DATE-TIME value
if the DATE-TIME is not either a UTC or a "floating" time.
The presence of the SOLIDUS character (US-ASCII decimal 47) as a
prefix, indicates that this TZID represents a 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.
The following are examples of this property parameter:
DTSTART;TZID=US-Eastern:19980119T020000
DTEND;TZID=US-Eastern:19980119T030000
The TZID property parameter MUST NOT be applied to DATE-TIME or TIME
properties whose time values are specified in UTC.
The use of local time in a DATE-TIME or TIME value without the TZID
property parameter is to be interpreted as a local time value,
regardless of the existence of "VTIMEZONE" calendar components in the
iCalendar object.
For more information see the sections on the data types DATE-TIME and
TIME.
4.2.20 Value Data Types
Parameter Name: VALUE
Purpose: To explicitly specify the data type format for a property
value.
Format Definition: The "VALUE" property parameter is defined by the
following notation:
valuetypeparam = "VALUE" "=" valuetype
valuetype = ("BINARY"
/ "BOOLEAN"
/ "CAL-ADDRESS"
/ "DATE"
/ "DATE-TIME"
/ "DURATION"
/ "FLOAT"
/ "INTEGER"
/ "PERIOD"
/ "RECUR"
/ "TEXT"
/ "TIME"
/ "URI"
/ "UTC-OFFSET"
/ x-name
; Some experimental iCalendar data type.
/ iana-token)
; Some other IANA registered iCalendar data type.
Description: The parameter specifies the data type and format of the
property value. The property values MUST be of a single value type.
For example, a "RDATE" property cannot have a combination of DATE-
TIME and TIME value types.
If the property's value is the default value type, then this
parameter need not be specified. However, if the property's default
value type is overridden by some other allowable value type, then
this parameter MUST be specified.
4.3 Property Value Data Types
The properties in an iCalendar object are strongly typed. The
definition of each property restricts the value to be one of the
value data types, or simply value types, defined in this section. The
value type for a property will either be specified implicitly as the
default value type or will be explicitly specified with the "VALUE"
parameter. If the value type of a property is one of the alternate
valid types, then it MUST be explicitly specified with the "VALUE"
parameter.
4.3.1 Binary
Value Name: BINARY
Purpose: This value type is used to identify properties that contain
a character encoding of inline binary data. For example, an inline
attachment of an object code might be included in an iCalendar
object.
Formal Definition: The value type is defined by the following
notation:
binary = *(4b-char) [b-end]
; A "BASE64" encoded character string, as defined by [RFC 2045].
b-end = (2b-char "==") / (3b-char "=")
b-char = ALPHA / DIGIT / "+" / "/"
Description: Property values with this value type MUST also include
the inline encoding parameter sequence of ";ENCODING=BASE64". That
is, all inline binary data MUST first be character encoded using the
"BASE64" encoding method defined in [RFC 2045]. No additional content
value encoding (i.e., BACKSLASH character encoding) is defined for
this value type.
Example: The following is an abridged example of a "BASE64" encoded
binary value data.
ATTACH;VALUE=BINARY;ENCODING=BASE64:MIICajCCAdOgAwIBAgICBEUwDQY
JKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlI
ENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZv
<...remainder of "BASE64" encoded binary data...>
4.3.2 Boolean
Value Name: BOOLEAN
Purpose: This value type is used to identify properties that contain
either a "TRUE" or "FALSE" Boolean value.
Formal Definition: The value type is defined by the following
notation:
boolean = "TRUE" / "FALSE"
Description: These values are case insensitive text. No additional
content value encoding (i.e., BACKSLASH character encoding) is
defined for this value type.
Example: The following is an example of a hypothetical property that
has a BOOLEAN value type:
GIBBERISH:TRUE
4.3.3 Calendar User Address
Value Name: CAL-ADDRESS
Purpose: This value type is used to identify properties that contain
a calendar user address.
Formal Definition: The value type is as defined by the following
notation:
cal-address = uri
Description: The value is a URI as defined by [RFC 1738] or any other
IANA registered form for a URI. When used to address an Internet
email transport address for a calendar user, the value MUST be a
MAILTO URI, as defined by [RFC 1738]. No additional content value
encoding (i.e., BACKSLASH character encoding) is defined for this
value type.
Example:
ATTENDEE:MAILTO:jane_doe@host.com
4.3.4 Date
Value Name: DATE
Purpose: This value type is used to identify values that contain a
calendar date.
Formal Definition: The value type is defined by the following
notation:
date = date-value
date-value = date-fullyear date-month date-mday
date-fullyear = 4DIGIT
date-month = 2DIGIT ;01-12
date-mday = 2DIGIT ;01-28, 01-29, 01-30, 01-31
;based on month/year
Description: If the property permits, multiple "date" values are
specified as a COMMA character (US-ASCII decimal 44) separated list
of values. The format for the value type is expressed as the [ISO
8601] complete representation, basic format for a calendar date. The
textual format specifies a four-digit year, two-digit month, and
two-digit day of the month. There are no separator characters between
the year, month and day component text.
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
Example: The following represents July 14, 1997:
19970714
4.3.5 Date-Time
Value Name: DATE-TIME
Purpose: This value type is used to identify values that specify a
precise calendar date and time of day.
Formal Definition: The value type is defined by the following
notation:
date-time = date "T" time ;As specified in the date and time
;value definitions
Description: If the property permits, multiple "date-time" values are
specified as a COMMA character (US-ASCII decimal 44) separated list
of values. No additional content value encoding (i.e., BACKSLASH
character encoding) is defined for this value type.
The "DATE-TIME" data type is used to identify values that contain a
precise calendar date and time of day. The format is based on the
[ISO 8601] complete representation, basic format for a calendar date
and time of day. The text format is a concatenation of the "date",
followed by the LATIN CAPITAL LETTER T character (US-ASCII decimal
84) time designator, followed by the "time" format.
The "DATE-TIME" data type expresses time values in three forms:
The form of date and time with UTC offset MUST NOT be used. For
example, the following is not valid for a date-time value:
DTSTART:19980119T230000-0800 ;Invalid time format
FORM #1: DATE WITH LOCAL TIME
The date with local time form is simply a date-time value that does
not contain the UTC designator nor does it reference a time zone. For
example, the following represents Janurary 18, 1998, at 11 PM:
DTSTART:19980118T230000
Date-time values of this type are said to be "floating" and are not
bound to any time zone in particular. They are used to represent the
same hour, minute, and second value regardless of which time zone is
currently being observed. For example, an event can be defined that
indicates that an individual will be busy from 11:00 AM to 1:00 PM
every day, no matter which time zone the person is in. In these
cases, a local time can be specified. The recipient of an iCalendar
object with a property value consisting of a local time, without any
relative time zone information, SHOULD interpret the value as being
fixed to whatever time zone the ATTENDEE is in at any given moment.
This means that two ATTENDEEs, in different time zones, receiving the
same event definition as a floating time, may be participating in the
event at different actual times. Floating time SHOULD only be used
where that is the reasonable behavior.
In most cases, a fixed time is desired. To properly communicate a
fixed time in a property value, either UTC time or local time with
time zone reference MUST be specified.
The use of local time in a DATE-TIME value without the TZID property
parameter is to be interpreted as floating time, regardless of the
existence of "VTIMEZONE" calendar components in the iCalendar object.
FORM #2: DATE WITH UTC TIME
The date with UTC time, or absolute time, is identified by a LATIN
CAPITAL LETTER Z suffix character (US-ASCII decimal 90), the UTC
designator, appended to the time value. For example, the following
represents January 19, 1998, at 0700 UTC:
DTSTART:19980119T070000Z
The TZID property parameter MUST NOT be applied to DATE-TIME
properties whose time values are specified in UTC.
FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE
The date and local time with reference to time zone information is
identified by the use the TZID property parameter to reference the
appropriate time zone definition. TZID is discussed in detail in the
section on Time Zone. For example, the following represents 2 AM in
New York on Janurary 19, 1998:
DTSTART;TZID=US-Eastern:19980119T020000
Example: The following represents July 14, 1997, at 1:30 PM in New
York City in each of the three time formats, using the "DTSTART"
property.
DTSTART:19970714T133000 ;Local time
DTSTART:19970714T173000Z ;UTC time
DTSTART;TZID=US-Eastern:19970714T133000 ;Local time and time
; zone reference
A time value MUST ONLY specify 60 seconds when specifying the
periodic "leap second" in the time value. For example:
COMPLETED:19970630T235960Z
4.3.6 Duration
Value Name: DURATION
Purpose: This value type is used to identify properties that contain
a duration of time.
Formal Definition: The value type is defined by the following
notation:
dur-value = (["+"] / "-") "P" (dur-date / dur-time / dur-week)
dur-date = dur-day [dur-time]
dur-time = "T" (dur-hour / dur-minute / dur-second)
dur-week = 1*DIGIT "W"
dur-hour = 1*DIGIT "H" [dur-minute]
dur-minute = 1*DIGIT "M" [dur-second]
dur-second = 1*DIGIT "S"
dur-day = 1*DIGIT "D"
Description: If the property permits, multiple "duration" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. The format is expressed as the [ISO 8601] basic format for
the duration of time. The format can represent durations in terms of
weeks, days, hours, minutes, and seconds.
No additional content value encoding (i.e., BACKSLASH character
encoding) are defined for this value type.
Example: A duration of 15 days, 5 hours and 20 seconds would be:
P15DT5H0M20S
A duration of 7 weeks would be:
P7W
4.3.7 Float
Value Name: FLOAT
Purpose: This value type is used to identify properties that contain
a real number value.
Formal Definition: The value type is defined by the following
notation:
float = (["+"] / "-") 1*DIGIT ["." 1*DIGIT]
Description: If the property permits, multiple "float" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values.
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
Example:
1000000.0000001
1.333
-3.14
4.3.8 Integer
Value Name:INTEGER
Purpose: This value type is used to identify properties that contain
a signed integer value.
Formal Definition: The value type is defined by the following
notation:
integer = (["+"] / "-") 1*DIGIT
Description: If the property permits, multiple "integer" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. The valid range for "integer" is -2147483648 to
2147483647. If the sign is not specified, then the value is assumed
to be positive.
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
Example:
1234567890
-1234567890
+1234567890
432109876
4.3.9 Period of Time
Value Name: PERIOD
Purpose: This value type is used to identify values that contain a
precise period of time.
Formal Definition: The data type is defined by the following
notation:
period = period-explicit / period-start
period-explicit = date-time "/" date-time
; [ISO 8601] complete representation basic format for a period of
; time consisting of a start and end. The start MUST be before the
; end.
period-start = date-time "/" dur-value
; [ISO 8601] complete representation basic format for a period of
; time consisting of a start and positive duration of time.
Description: If the property permits, multiple "period" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. There are two forms of a period of time. First, a period
of time is identified by its start and its end. This format is
expressed as the [ISO 8601] complete representation, basic format for
"DATE-TIME" start of the period, followed by a SOLIDUS character
(US-ASCII decimal 47), followed by the "DATE-TIME" of the end of the
period. The start of the period MUST be before the end of the period.
Second, a period of time can also be defined by a start and a
positive duration of time. The format is expressed as the [ISO 8601]
complete representation, basic format for the "DATE-TIME" start of
the period, followed by a SOLIDUS character (US-ASCII decimal 47),
followed by the [ISO 8601] basic format for "DURATION" of the period.
Example: The period starting at 18:00:00 UTC, on January 1, 1997 and
ending at 07:00:00 UTC on January 2, 1997 would be:
19970101T180000Z/19970102T070000Z
The period start at 18:00:00 on January 1, 1997 and lasting 5 hours
and 30 minutes would be:
19970101T180000Z/PT5H30M
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
4.3.10 Recurrence Rule
Value Name: RECUR
Purpose: This value type is used to identify properties that contain
a recurrence rule specification.
Formal Definition: The value type is defined by the following
notation:
recur = "FREQ"=freq *(
; either UNTIL or COUNT may appear in a 'recur',
; but UNTIL and COUNT MUST NOT occur in the same 'recur'
( ";" "UNTIL" "=" enddate ) /
( ";" "COUNT" "=" 1*DIGIT ) /
; the rest of these keywords are optional,
; but MUST NOT occur more than once
( ";" "INTERVAL" "=" 1*DIGIT ) /
( ";" "BYSECOND" "=" byseclist ) /
( ";" "BYMINUTE" "=" byminlist ) /
( ";" "BYHOUR" "=" byhrlist ) /
( ";" "BYDAY" "=" bywdaylist ) /
( ";" "BYMONTHDAY" "=" bymodaylist ) /
( ";" "BYYEARDAY" "=" byyrdaylist ) /
( ";" "BYWEEKNO" "=" bywknolist ) /
( ";" "BYMONTH" "=" bymolist ) /
( ";" "BYSETPOS" "=" bysplist ) /
( ";" "WKST" "=" weekday ) /
( ";" x-name "=" text )
)
freq = "SECONDLY" / "MINUTELY" / "HOURLY" / "DAILY"
/ "WEEKLY" / "MONTHLY" / "YEARLY"
enddate = date
enddate =/ date-time ;An UTC value
byseclist = seconds / ( seconds *("," seconds) )
seconds = 1DIGIT / 2DIGIT ;0 to 59
byminlist = minutes / ( minutes *("," minutes) )
minutes = 1DIGIT / 2DIGIT ;0 to 59
byhrlist = hour / ( hour *("," hour) )
hour = 1DIGIT / 2DIGIT ;0 to 23
bywdaylist = weekdaynum / ( weekdaynum *("," weekdaynum) )
weekdaynum = [([plus] ordwk / minus ordwk)] weekday
plus = "+"
minus = "-"
ordwk = 1DIGIT / 2DIGIT ;1 to 53
weekday = "SU" / "MO" / "TU" / "WE" / "TH" / "FR" / "SA"
;Corresponding to SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY,
;FRIDAY, SATURDAY and SUNDAY days of the week.
bymodaylist = monthdaynum / ( monthdaynum *("," monthdaynum) )
monthdaynum = ([plus] ordmoday) / (minus ordmoday)
ordmoday = 1DIGIT / 2DIGIT ;1 to 31
byyrdaylist = yeardaynum / ( yeardaynum *("," yeardaynum) )
yeardaynum = ([plus] ordyrday) / (minus ordyrday)
ordyrday = 1DIGIT / 2DIGIT / 3DIGIT ;1 to 366
bywknolist = weeknum / ( weeknum *("," weeknum) )
weeknum = ([plus] ordwk) / (minus ordwk)
bymolist = monthnum / ( monthnum *("," monthnum) )
monthnum = 1DIGIT / 2DIGIT ;1 to 12
bysplist = setposday / ( setposday *("," setposday) )
setposday = yeardaynum
Description: If the property permits, multiple "recur" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. The value type is a structured value consisting of a list
of one or more recurrence grammar parts. Each rule part is defined by
a NAME=VALUE pair. The rule parts are separated from each other by
the SEMICOLON character (US-ASCII decimal 59). The rule parts are not
ordered in any particular sequence. Individual rule parts MUST only
be specified once.
The FREQ rule part identifies the type of recurrence rule. This rule
part MUST be specified in the recurrence rule. Valid values include
SECONDLY, to specify repeating events based on an interval of a
second or more; MINUTELY, to specify repeating events based on an
interval of a minute or more; HOURLY, to specify repeating events
based on an interval of an hour or more; DAILY, to specify repeating
events based on an interval of a day or more; WEEKLY, to specify
repeating events based on an interval of a week or more; MONTHLY, to
specify repeating events based on an interval of a month or more; and
YEARLY, to specify repeating events based on an interval of a year or
more.
The INTERVAL rule part contains a positive integer representing how
often the recurrence rule repeats. The default value is "1", meaning
every second for a SECONDLY rule, or every minute for a MINUTELY
rule, every hour for an HOURLY rule, every day for a DAILY rule,
every week for a WEEKLY rule, every month for a MONTHLY rule and
every year for a YEARLY rule.
The UNTIL rule part defines a date-time value which bounds the
recurrence rule in an inclusive manner. If the value specified by
UNTIL is synchronized with the specified recurrence, this date or
date-time becomes the last instance of the recurrence. If specified
as a date-time value, then it MUST be specified in an UTC time
format. If not present, and the COUNT rule part is also not present,
the RRULE is considered to repeat forever.
The COUNT rule part defines the number of occurrences at which to
range-bound the recurrence. The "DTSTART" property value, if
specified, counts as the first occurrence.
The BYSECOND rule part specifies a COMMA character (US-ASCII decimal
44) separated list of seconds within a minute. Valid values are 0 to
59. The BYMINUTE rule part specifies a COMMA character (US-ASCII
decimal 44) separated list of minutes within an hour. Valid values
are 0 to 59. The BYHOUR rule part specifies a COMMA character (US-
ASCII decimal 44) separated list of hours of the day. Valid values
are 0 to 23.
The BYDAY rule part specifies a COMMA character (US-ASCII decimal 44)
separated list of days of the week; MO indicates Monday; TU indicates
Tuesday; WE indicates Wednesday; TH indicates Thursday; FR indicates
Friday; SA indicates Saturday; SU indicates Sunday.
Each BYDAY value can also be preceded by a positive (+n) or negative
(-n) integer. If present, this indicates the nth occurrence of the
specific day within the MONTHLY or YEARLY RRULE. For example, within
a MONTHLY rule, +1MO (or simply 1MO) represents the first Monday
within the month, whereas -1MO represents the last Monday of the
month. If an integer modifier is not present, it means all days of
this type within the specified frequency. For example, within a
MONTHLY rule, MO represents all Mondays within the month.
The BYMONTHDAY rule part specifies a COMMA character (ASCII decimal
44) separated list of days of the month. Valid values are 1 to 31 or
-31 to -1. For example, -10 represents the tenth to the last day of
the month.
The BYYEARDAY rule part specifies a COMMA character (US-ASCII decimal
44) separated list of days of the year. Valid values are 1 to 366 or
-366 to -1. For example, -1 represents the last day of the year
(December 31st) and -306 represents the 306th to the last day of the
year (March 1st).
The BYWEEKNO rule part specifies a COMMA character (US-ASCII decimal
44) separated list of ordinals specifying weeks of the year. Valid
values are 1 to 53 or -53 to -1. This corresponds to weeks according
to week numbering as defined in [ISO 8601]. A week is defined as a
seven day period, starting on the day of the week defined to be the
week start (see WKST). Week number one of the calendar year is the
first week which contains at least four (4) days in that calendar
year. This rule part is only valid for YEARLY rules. For example, 3
represents the third week of the year.
Note: Assuming a Monday week start, week 53 can only occur when
Thursday is January 1 or if it is a leap year and Wednesday is
January 1.
The BYMONTH rule part specifies a COMMA character (US-ASCII decimal
44) separated list of months of the year. Valid values are 1 to 12.
The WKST rule part specifies the day on which the workweek starts.
Valid values are MO, TU, WE, TH, FR, SA and SU. This is significant
when a WEEKLY RRULE has an interval greater than 1, and a BYDAY rule
part is specified. This is also significant when in a YEARLY RRULE
when a BYWEEKNO rule part is specified. The default value is MO.
The BYSETPOS rule part specifies a COMMA character (US-ASCII decimal
44) separated list of values which corresponds to the nth occurrence
within the set of events specified by the rule. Valid values are 1 to
366 or -366 to -1. It MUST only be used in conjunction with another
BYxxx rule part. For example "the last work day of the month" could
be represented as:
RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1
Each BYSETPOS value can include a positive (+n) or negative (-n)
integer. If present, this indicates the nth occurrence of the
specific occurrence within the set of events specified by the rule.
If BYxxx rule part values are found which are beyond the available
scope (ie, BYMONTHDAY=30 in February), they are simply ignored.
Information, not contained in the rule, necessary to determine the
various recurrence instance start time and dates are derived from the
Start Time (DTSTART) entry attribute. For example,
"FREQ=YEARLY;BYMONTH=1" doesn't specify a specific day within the
month or a time. This information would be the same as what is
specified for DTSTART.
BYxxx rule parts modify the recurrence in some manner. BYxxx rule
parts for a period of time which is the same or greater than the
frequency generally reduce or limit the number of occurrences of the
recurrence generated. For example, "FREQ=DAILY;BYMONTH=1" reduces the
number of recurrence instances from all days (if BYMONTH tag is not
present) to all days in January. BYxxx rule parts for a period of
time less than the frequency generally increase or expand the number
of occurrences of the recurrence. For example,
"FREQ=YEARLY;BYMONTH=1,2" increases the number of days within the
yearly recurrence set from 1 (if BYMONTH tag is not present) to 2.
If multiple BYxxx rule parts are specified, then after evaluating the
specified FREQ and INTERVAL rule parts, the BYxxx rule parts are
applied to the current set of evaluated occurrences in the following
order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY, BYDAY, BYHOUR,
BYMINUTE, BYSECOND and BYSETPOS; then COUNT and UNTIL are evaluated.
Here is an example of evaluating multiple BYxxx rule parts.
DTSTART;TZID=US-Eastern:19970105T083000
RRULE:FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=SU;BYHOUR=8,9;
BYMINUTE=30
First, the "INTERVAL=2" would be applied to "FREQ=YEARLY" to arrive
at "every other year". Then, "BYMONTH=1" would be applied to arrive
at "every January, every other year". Then, "BYDAY=SU" would be
applied to arrive at "every Sunday in January, every other year".
Then, "BYHOUR=8,9" would be applied to arrive at "every Sunday in
January at 8 AM and 9 AM, every other year". Then, "BYMINUTE=30"
would be applied to arrive at "every Sunday in January at 8:30 AM and
9:30 AM, every other year". Then, lacking information from RRULE, the
second is derived from DTSTART, to end up in "every Sunday in January
at 8:30:00 AM and 9:30:00 AM, every other year". Similarly, if the
BYMINUTE, BYHOUR, BYDAY, BYMONTHDAY or BYMONTH rule part were
missing, the appropriate minute, hour, day or month would have been
retrieved from the "DTSTART" property.
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
Example: The following is a rule which specifies 10 meetings which
occur every other day:
FREQ=DAILY;COUNT=10;INTERVAL=2
There are other examples specified in the "RRULE" specification.
4.3.11 Text
Value Name: TEXT
Purpose This value type is used to identify values that contain human
readable text.
Formal Definition: The character sets supported by this revision of
iCalendar are UTF-8 and US ASCII thereof. The applicability to other
character sets is for future work. The value type is defined by the
following notation.
text = *(TSAFE-CHAR / ":" / DQUOTE / ESCAPED-CHAR)
; Folded according to description above
ESCAPED-CHAR = "\\" / "\;" / "\," / "\N" / "\n")
; \\ encodes \, \N or \n encodes newline
; \; encodes ;, \, encodes ,
TSAFE-CHAR = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B
%x5D-7E / NON-US-ASCII
; Any character except CTLs not needed by the current
; character set, DQUOTE, ";", ":", "\", ","
Note: Certain other character sets may require modification of the
above definitions, but this is beyond the scope of this document.
Description: If the property permits, multiple "text" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values.
The language in which the text is represented can be controlled by
the "LANGUAGE" property parameter.
An intentional formatted text line break MUST only be included in a
"TEXT" property value by representing the line break with the
character sequence of BACKSLASH (US-ASCII decimal 92), followed by a
LATIN SMALL LETTER N (US-ASCII decimal 110) or a LATIN CAPITAL LETTER
N (US-ASCII decimal 78), that is "\n" or "\N".
The "TEXT" property values may also contain special characters that
are used to signify delimiters, such as a COMMA character for lists
of values or a SEMICOLON character for structured values. In order to
support the inclusion of these special characters in "TEXT" property
values, they MUST be escaped with a BACKSLASH character. A BACKSLASH
character (US-ASCII decimal 92) in a "TEXT" property value MUST be
escaped with another BACKSLASH character. A COMMA character in a
"TEXT" property value MUST be escaped with a BACKSLASH character
(US-ASCII decimal 92). A SEMICOLON character in a "TEXT" property
value MUST be escaped with a BACKSLASH character (US-ASCII decimal
92). However, a COLON character in a "TEXT" property value SHALL NOT
be escaped with a BACKSLASH character.Example: A multiple line value
of:
Project XYZ Final Review
Conference Room - 3B
Come Prepared.
would be represented as:
Project XYZ Final Review\nConference Room - 3B\nCome Prepared.
4.3.12 Time
Value Name: TIME
Purpose: This value type is used to identify values that contain a
time of day.
Formal Definition: The data type is defined by the following
notation:
time = time-hour time-minute time-second [time-utc]
time-hour = 2DIGIT ;00-23
time-minute = 2DIGIT ;00-59
time-second = 2DIGIT ;00-60
;The "60" value is used to account for "leap" seconds.
time-utc = "Z"
Description: If the property permits, multiple "time" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values. No additional content value encoding (i.e., BACKSLASH
character encoding) is defined for this value type.
The "TIME" data type is used to identify values that contain a time
of day. The format is based on the [ISO 8601] complete
representation, basic format for a time of day. The text format
consists of a two-digit 24-hour of the day (i.e., values 0-23), two-
digit minute in the hour (i.e., values 0-59), and two-digit seconds
in the minute (i.e., values 0-60). The seconds value of 60 MUST only
to be used to account for "leap" seconds. Fractions of a second are
not supported by this format.
In parallel to the "DATE-TIME" definition above, the "TIME" data type
expresses time values in three forms:
The form of time with UTC offset MUST NOT be used. For example, the
following is NOT VALID for a time value:
230000-0800 ;Invalid time format
FORM #1 LOCAL TIME
The local time form is simply a time value that does not contain the
UTC designator nor does it reference a time zone. For example, 11:00
PM:
230000
Time values of this type are said to be "floating" and are not bound
to any time zone in particular. They are used to represent the same
hour, minute, and second value regardless of which time zone is
currently being observed. For example, an event can be defined that
indicates that an individual will be busy from 11:00 AM to 1:00 PM
every day, no matter which time zone the person is in. In these
cases, a local time can be specified. The recipient of an iCalendar
object with a property value consisting of a local time, without any
relative time zone information, SHOULD interpret the value as being
fixed to whatever time zone the ATTENDEE is in at any given moment.
This means that two ATTENDEEs may participate in the same event at
different UTC times; floating time SHOULD only be used where that is
reasonable behavior.
In most cases, a fixed time is desired. To properly communicate a
fixed time in a property value, either UTC time or local time with
time zone reference MUST be specified.
The use of local time in a TIME value without the TZID property
parameter is to be interpreted as a local time value, regardless of
the existence of "VTIMEZONE" calendar components in the iCalendar
object.
FORM #2: UTC TIME
UTC time, or absolute time, is identified by a LATIN CAPITAL LETTER Z
suffix character (US-ASCII decimal 90), the UTC designator, appended
to the time value. For example, the following represents 07:00 AM
UTC:
070000Z
The TZID property parameter MUST NOT be applied to TIME properties
whose time values are specified in UTC.
FORM #3: LOCAL TIME AND TIME ZONE REFERENCE
The local time with reference to time zone information form is
identified by the use the TZID property parameter to reference the
appropriate time zone definition. TZID is discussed in detail in the
section on Time Zone.
Example: The following represents 8:30 AM in New York in Winter, five
hours behind UTC, in each of the three formats using the "X-
TIMEOFDAY" non-standard property:
X-TIMEOFDAY:083000
X-TIMEOFDAY:133000Z
X-TIMEOFDAY;TZID=US-Eastern:083000
4.3.13 URI
Value Name: URI
Purpose: This value type is used to identify values that contain a
uniform resource identifier (URI) type of reference to the property
value.
Formal Definition: The data type is defined by the following
notation:
uri =
Description: This data type might be used to reference binary
information, for values that are large, or otherwise undesirable to
include directly in the iCalendar object.
The URI value formats in RFC 1738, RFC 2111 and any other IETF
registered value format can be specified.
Any IANA registered URI format can be used. These include, but are
not limited to, those defined in RFC 1738 and RFC 2111.
When a property parameter value is a URI value type, the URI MUST be
specified as a quoted-string value.
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
Example: The following is a URI for a network file:
http://host1.com/my-report.txt
4.3.14 UTC Offset
Value Name: UTC-OFFSET
Purpose: This value type is used to identify properties that contain
an offset from UTC to local time.
Formal Definition: The data type is defined by the following
notation:
utc-offset = time-numzone ;As defined above in time data type
time-numzone = ("+" / "-") time-hour time-minute [time-
second]
Description: The PLUS SIGN character MUST be specified for positive
UTC offsets (i.e., ahead of UTC). The value of "-0000" and "-000000"
are not allowed. The time-second, if present, may not be 60; if
absent, it defaults to zero.
No additional content value encoding (i.e., BACKSLASH character
encoding) is defined for this value type.
Example: The following UTC offsets are given for standard time for
New York (five hours behind UTC) and Geneva (one hour ahead of UTC):
-0500
+0100
4.4 iCalendar Object
The Calendaring and Scheduling Core Object is a collection of
calendaring and scheduling information. Typically, this information
will consist of a single iCalendar object. However, multiple
iCalendar objects can be sequentially grouped together. The first
line and last line of the iCalendar object MUST contain a pair of
iCalendar object delimiter strings. The syntax for an iCalendar
object is as follows:
icalobject = 1*("BEGIN" ":" "VCALENDAR" CRLF
icalbody
"END" ":" "VCALENDAR" CRLF)
The following is a simple example of an iCalendar object:
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
BEGIN:VEVENT
DTSTART:19970714T170000Z
DTEND:19970715T035959Z
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR
4.5 Property
A property is the definition of an individual attribute describing a
calendar or a calendar component. A property takes the form defined
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.
4.6 Calendar Components
The body of the iCalendar object consists of a sequence of calendar
properties and one or more calendar components. The calendar
properties are attributes that apply to the calendar as a whole. The
calendar components are collections of properties that express a
particular calendar semantic. For example, the calendar component can
specify an event, 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
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.
4.6.1 Event Component
Component Name: "VEVENT"
Purpose: Provide a grouping of component properties that describe an
event.
Format Definition: A "VEVENT" calendar component is defined by the
following notation:
eventc = "BEGIN" ":" "VEVENT" CRLF
eventprop *alarmc
"END" ":" "VEVENT" CRLF
eventprop = *(
; the following are optional,
; but MUST NOT occur more than once
class / created / description / dtstart / 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
)
Description: A "VEVENT" calendar component is a grouping of component
properties, and possibly including "VALARM" calendar components, that
represents a scheduled amount of time on a calendar. For example, it
can be an activity; such as a one-hour long, department meeting from
8:00 AM to 9:00 AM, tomorrow. Generally, an event will take up time
on an individual calendar. Hence, the event will appear as an opaque
interval in a search for busy time. Alternately, the event can have
its Time Transparency set to "TRANSPARENT" in order to prevent
blocking of the event in searches for busy time.
The "VEVENT" is also the calendar component used to specify an
anniversary or daily reminder within a calendar. These events have a
DATE value type for the "DTSTART" property instead of the default
data type of DATE-TIME. 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: 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
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
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
4.6.2 To-do Component
Component Name: VTODO
Purpose: Provide a grouping of calendar properties that describe a
to-do.
Formal Definition: A "VTODO" calendar component is defined by the
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
)
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.
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
4.6.3 Journal Component
Component Name: VJOURNAL
Purpose: Provide a grouping of component properties that describe a
journal entry.
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
)
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
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
4.6.4 Free/Busy Component
Component Name: VFREEBUSY
Purpose: Provide a grouping of component properties that describe
either a request for free/busy time, describe a response to a request
for free/busy time or describe a published set of busy time.
Formal Definition: A "VFREEBUSY" calendar component is defined by the
following notation:
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
)
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
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
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