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iCalendar (RFC 5545)
Abstract
This document defines the iCalendar data format for representing and exchanging calendaring and scheduling information such as events, to-dos, journal entries, and free/busy information, independent of any particular calendar service or protocol.
RFC 5545 supercedes the original iCalendar specification , RFC 2445.
Author
B. Desruisseaux, Ed., Oracle, September 2009
3.8.3.1. Time Zone Identifier
Property Name
TZID
Purpose
This property specifies the text value that uniquely identifies the "VTIMEZONE" calendar component in the scope of an iCalendar object.
Value Type
TEXT
Property Parameters
IANA and non-standard property parameters can be specified on this property.
Conformance
This property MUST be specified in a "VTIMEZONE" calendar component.
Description
This is the label by which a time zone calendar component is referenced by any iCalendar properties whose value type is either DATE-TIME or TIME and not intended to specify a UTC or a "floating" time. The presence of the SOLIDUS character as a prefix, indicates that this "TZID" represents an unique ID in a globally defined time zone registry (when such registry is defined).
Note: This document does not define a naming convention for time zone identifiers. Implementers may want to use the naming conventions defined in existing time zone specifications such as the public-domain TZ database [TZDB]. The specification of globally unique time zone identifiers is not addressed by this document and is left for future study.
Format Definition
This property is defined by the following notation:
tzid = "TZID" tzidpropparam ":" [tzidprefix] text CRLF
tzidpropparam = *(";" other-param)
;tzidprefix = "/" ; Defined previously. Just listed here for reader convenience.
Example
The following are examples of non-globally unique time zone identifiers:
TZID:America/New_York
TZID:America/Los_Angeles
The following is an example of a fictitious globally unique time zone identifier:
TZID:/example.org/America/New_York
3.8.3.2. Time Zone Name
Property Name
TZNAME
Purpose
This property specifies the customary designation for a time zone description.
Value Type
TEXT
Property Parameters
IANA, non-standard, and language property parameters can be specified on this property.
Conformance
This property can be specified in "STANDARD" and "DAYLIGHT" sub-components.
Description
This property specifies a customary name that can be used when displaying dates that occur during the observance defined by the time zone sub-component.
Format Definition
This property is defined by the following notation:
tzname = "TZNAME" tznparam ":" text CRLF
tznparam = *(
;
; The following is OPTIONAL,
; but MUST NOT occur more than once.
;
(";" languageparam) /
;
; The following is OPTIONAL,
; and MAY occur more than once.
;
(";" other-param)
;
)
Example
The following are examples of this property
TZNAME:EST
TZNAME;LANGUAGE=fr-CA:HNE
3.8.3.3. Time Zone Offset From
Property Name
TZOFFSETFROM
Purpose
This property specifies the offset that is in use prior to this time zone observance.
Value Type
UTC-OFFSET
Property Parameters
IANA and non-standard property parameters can be specified on this property.
Conformance
This property MUST be specified in "STANDARD" and "DAYLIGHT" sub-components.
Description
This property specifies the offset that is in use prior to this time observance. It is used to calculate the absolute time at which the transition to a given observance takes place. This property MUST only be specified in a "VTIMEZONE" calendar component. A "VTIMEZONE" calendar component MUST include this property. The property value is a signed numeric indicating the number of hours and possibly minutes from UTC. Positive numbers represent time zones east of the prime meridian, or ahead of UTC. Negative numbers represent time zones west of the prime meridian, or behind UTC.
Format Definition
This property is defined by the following notation:
tzoffsetfrom = "TZOFFSETFROM" frmparam ":" utc-offset CRLF
frmparam = *(";" other-param)
Example
The following are examples of this property
TZOFFSETFROM:-0500
TZOFFSETFROM:+1345
3.8.3.4. Time Zone Offset To
Property Name
TZOFFSETTO
Purpose
This property specifies the offset that is in use in this time zone observance.
Value Type
UTC-OFFSET
Property Parameters
IANA and non-standard property parameters can be specified on this property.
Conformance
This property MUST be specified in "STANDARD" and "DAYLIGHT" sub-components.
Description
This property specifies the offset that is in use in this time zone observance. It is used to calculate the absolute time for the new observance. The property value is a signed numeric indicating the number of hours and possibly minutes from UTC. Positive numbers represent time zones east of the prime meridian, or ahead of UTC. Negative numbers represent time zones west of the prime meridian, or behind UTC.
Format Definition
This property is defined by the following notation:
tzoffsetto = "TZOFFSETTO" toparam ":" utc-offset CRLF
toparam = *(";" other-param)
Example
The following are examples of this property
TZOFFSETTO:-0400
TZOFFSETTO:+1245
This document was automatically converted to XHTML using an RFC to HTML converter with the original text document at the Internet Engineering Task Force web site at ietf.org . The original text document should be referred to if there are any errors or discrepancies found in this document.
Need to test your iCalendar feeds?
The iCalendar Validator provides developers and testers a method to validate their iCalendar feeds, which can take data from either a URL, file or text snippet and compare it against the RFC 5545 specification. We believe we have one of the best iCalendar validation tools available on the internet. More information about the validator can be found here.