| Internet-Draft | iCalendar JSCalendar Extensions | July 2025 |
| Stepanek | Expires 21 January 2026 | [Page] |
This document defines a set of new elements for iCalendar and extends the use of existing ones. Their main purpose is to extend the semantics of iCalendar with elements defined in JSCalendar, but the new definitions also aim to be useful within just the iCalendar format. This document updates RFC 5545 ("Internet Calendaring and Scheduling Core Object Specification (iCalendar)").¶
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The JSCalendar [I-D.stepanek-jscalendarbis] format aims to be an alternative to the iCalendar [RFC5545] format for representation of calendaring data. As such, it introduces new semantics that are not covered in the current definition of iCalendar and its various extensions. Converting calendaring data between the two formats is defined in [I-D.ietf-calext-jscalendar-icalendar] with the goal of not losing any semantics during conversion. To achieve this, this document defines new elements iCalendar and extends existing definitions. Doing so, it follows the recommendations for introducing new iCalendar elements as specified in Section 3 of [RFC7986].¶
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 interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
This specification deprecates the "GEO" property and introduces the "COORDINATES" (Section 4.1) property to replace it. Implementations SHOULD NOT use the "GEO" property to represent spatial coordinates. Instead, they SHOULD specify the "COORDINATES" property in a "VLOCATION" component [RFC9073] (Section 7.2). They MAY additionally specify a "GEO" property in a "VEVENT" or "VTODO" component, in which case its "DERIVED" parameter [RFC9073] (Section 5.3) MUST have value "TRUE".¶
The remainder of this section documents the rationale for deprecating the "GEO" property:¶
The "GEO" property definition dates back to 1998, a time at which multiple internet protocols and data formats incorporated spatial coordinates in slightly different formats, making interoperability difficult. This got addressed in 2010 in [RFC5870], which introduced a Uniform Resource Identifier (URI) for geographic locations. The 'geo' URI scheme not only improves interoperability but also allows for richer information than the "GEO" property value, e.g. it supports specifying the location altitude and the spatial uncertainty of the coordinates.¶
Alternatively to deprecating, this specification could have updated the "GEO" property to allow its property value type to be URI. This turned out to not interoperate, as implementations tended to reject such iCalendar data as invalid. This was regardless if the "GEO" property was specified in a "VEVENT" component, or if it was specified in iCalendar components that were unsupported by the implementation (e.g. an implementation that was unaware of the "VLOCATION" component still rejected the "GEO" property with value type URI in that component as invalid). Introducing a new property turned out to better interoperate with such systems.¶
This document updates the definition of the "VLOCATION" component. It allows to specify the newly defined "COORDINATES" property (Section 4.1) at most once in a "VLOCATION" component. It appends the following to the "Format Definition" of the "VLOCATION" component, defined in Section 7.2 of [RFC9073]:¶
locprop /= *(
;
; The following is OPTIONAL
; but MUST NOT occur more than once.
;
coord
;
)
¶
The "coord" ABNF is defined in Section 4.1.¶
This property represents spatial (geographic) coordinates. In contrast to the the "GEO" property, this property allows to represent not only latitude and longitude but also altitude of a location. In addition, it supports to indicate the uncertainty of the coordinates, is interoperable with other internet standards making use of spatial information, and is extensible, such as for use with other coordinate reference systems. The property value MUST a URI in the "geo" URI scheme, as defined in [RFC5870] and updates.¶
coord = "COORDINATES" coordparam ":" uri CRLF
coordparam = *(
;
; The following is REQUIRED,
; but MUST NOT occur more than once.
;
(";" "VALUE" "=" "URI") /
;
; The following is OPTIONAL,
; and MAY occur more than once.
;
(";" other-param)
;
)
¶
The following is an example of this property:¶
COORDINATES;VALUE=URI:geo:48.198634,16.371648;crs=wgs84;u=40¶
This indicates that the exact time span is not important to display when rendering this calendar object. An example of this is an event that occurs over a full or almost full day, but in contrast to a DATE value is limited to a specific time zone or business hours. While the time component is important for free-busy calculations and checking for scheduling clashes, calendars may choose to display it as an all-day event, or display the object separately to other objects to enhance the user's view of their schedule.¶
This property only is for presentation purposes, it does not have any impact on the temporal span or value type of a calendar object.¶
This property MAY be specified on VEVENT components where the DTSTART property is of type DATE-TIME, or in VTODO components where either the DTSTART or DUE property is specified and has type DATE-TIME. In all other cases it MUST NOT be set. If this property is set, its property value MUST be "TRUE", e.g. it MUST be omitted rather than having value "FALSE".¶
Implementations that are unaware of the "SHOW-WITHOUT-TIME" property might inadvertently preserve this property when changing a calendar object's temporal type from DATE-TIME to DATE. Implementations SHOULD therefore ignore rather than reject the incorrectly specified SHOW-WITHOUT-TIME property. They MUST NOT preserve the ill-specified property in the calendaring data.¶
showwt = "SHOW-WITHOUT-TIME" showwtparam ":" "TRUE" CRLF
showwtparam = *(
;
; The following is REQUIRED,
; but MUST NOT occur more than once.
;
(";" "VALUE" "=" "BOOLEAN") /
;
; The following is OPTIONAL,
; and MAY occur more than once.
;
(";" other-param)
;
)
¶
SHOW-WITHOUT-TIME;VALUE=BOOLEAN:TRUE¶
This specification extends [RFC5545]. The same security considerations as outlined in Section 7 of [RFC5545] apply.¶