| Internet-Draft | JSCalendar | May 2025 |
| Jenkins & Stepanek | Expires 14 November 2025 | [Page] |
This specification defines a data model and JSON representation of calendar data that can be used for storage and data exchange in a calendaring and scheduling environment. It aims to be an alternative and, over time, successor to the widely deployed iCalendar data format. It also aims to be unambiguous, extendable, and simple to process. In contrast to the jCal format, which is also based on JSON, JSCalendar is not a direct mapping from iCalendar but defines the data model independently and expands semantics where appropriate.¶
This note is to be removed before publishing as an RFC.¶
Differences from RFC 8984 are documented in Appendix A.¶
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."¶
This Internet-Draft will expire on 14 November 2025.¶
Copyright (c) 2025 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
This document defines a data model for calendar event and task objects, or groups of such objects, in electronic calendar applications and systems. The format aims to be unambiguous, extendable, and simple to process.¶
The key design considerations for this data model are as follows:¶
The representation of this data model is defined in the Internet JSON (I-JSON) format [RFC7493], which is a strict subset of the JSON data interchange format [RFC8259]. Using JSON is mostly a pragmatic choice: its widespread use makes JSCalendar easier to adopt and the ready availability of production-ready JSON implementations eliminates a whole category of parser-related interoperability issues, which iCalendar has often suffered from.¶
The iCalendar data format [RFC5545], a widely deployed interchange format for calendaring and scheduling data, has served calendaring vendors for a long time but contains some ambiguities and pitfalls that cannot be overcome without backward-incompatible changes.¶
Sources of implementation errors include the following:¶
In recent years, many new products and services have appeared that wish to use a JSON representation of calendar data within their APIs. The JSON format for iCalendar data, jCal [RFC7265], is a direct mapping between iCalendar and JSON. In its effort to represent full iCalendar semantics, it inherits all the same pitfalls and uses a complicated JSON structure.¶
As a consequence, since the standardization of jCal, the majority of implementations and service providers either kept using iCalendar or came up with their own proprietary JSON representations, which are incompatible with each other and often suffer from common pitfalls, such as storing event start times in UTC (which become incorrect if the time zone's rules change in the future). JSCalendar meets the demand for JSON-formatted calendar data that is free of such known problems and provides a standard representation as an alternative to the proprietary formats.¶
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.¶
The underlying format used for this specification is JSON. Consequently, the terms "object" and "array" as well as the four primitive types (strings, numbers, booleans, and null) are to be interpreted as described in Section 1 of [RFC8259].¶
Some examples in this document contain "partial" JSON documents used for illustrative purposes. In these examples, an ellipsis "..." is used to indicate a portion of the document that has been removed for compactness.¶
This section defines the notation for JSCalendar properties and types.¶
Type signatures are given for all JSON values in this document. The following conventions are used:¶
*:String:Number:Boolean:A:A.¶
A[B]:A and the values are all of type B for a JSON object.¶
A[]:A¶
A|B:A or of type B.¶
Other types may also be given; their representations are defined elsewhere in this document.¶
Object properties may also have a set of attributes defined along with the type signature. These have the following meanings:¶
mandatory:optional:default:defaultType:Every JSCalendar object has the following JSON object member:¶
The purpose of the @type property is to help implementations identify which JSCalendar object type a given JSON object represents. Implementations MUST validate that JSON objects with this property conform to the specification of the JSCalendar object type of that name.¶
In many cases, the @type property value is implied by where the object occurs in JSCalendar data. Assuming that both A and B are JSCalendar object types:¶
A MAY have the @type property set. If the @type property is not set, then its value is implied to be A.¶
A|B (defaultType: A) MAY have the @type property set if it is an instance of A. It MUST have the @type property set if it is an instance of B. If instead the defaultType attribute is not defined, then the @type property MUST also be set for A.¶
An object definition MAY require the @type property to be set regardless of the above definitions, e.g. this document requires the @type property to be set for the Event, Task and Group object types.¶
In addition to the standard JSON data types, the following data types are used in this specification:¶
Where Id is given as a data type, it means a String of at least 1 and a maximum of 255 octets in size, and it MUST only contain characters from the "URL and Filename Safe" base64url alphabet, as defined in Section 5 of [RFC4648], excluding the pad character (=). This means the allowed characters are the ASCII alphanumeric characters (A-Za-z0-9), hyphen (-), and underscore (_).¶
In many places in JSCalendar, a JSON map is used where the map keys are of type Id and the map values are all the same type of object. This construction represents an unordered set of objects, with the added advantage that each entry has a name (the corresponding map key). This allows for more concise patching of objects, and, when applicable, for the objects in question to be referenced from other objects within the JSCalendar object.¶
Unless otherwise specified for a particular property, there are no uniqueness constraints on an Id value (other than, of course, the requirement that you cannot have two values with the same key within a single JSON map). For example, two Event objects might use the same Ids in their respective links properties or, within the same Event object, the same Id could appear in the participants and alerts properties. These situations do not imply any semantic connections among the objects.¶
Where Int is given as a data type, it means an integer in the range -253+1 <= value <= 253-1, the safe range for integers stored in a floating-point double, represented as a JSON Number.¶
Where UnsignedInt is given as a data type, it means an integer in the range 0 <= value <= 253-1, represented as a JSON Number.¶
This is a string in the date-time [RFC3339] format, with the further restrictions that any letters MUST be in uppercase, and the time offset MUST be the character Z. Fractional second values MUST NOT be included unless non-zero and MUST NOT have trailing zeros, to ensure there is only a single representation for each date-time.¶
For example, 2010-10-10T10:10:10.003Z is conformant, but 2010-10-10T10:10:10.000Z is invalid and is correctly encoded as 2010-10-10T10:10:10Z.¶
This is a date-time string with no time zone/offset information. It is otherwise in the same format as UTCDateTime, including fractional seconds. For example, 2006-01-02T15:04:05 and 2006-01-02T15:04:05.003 are both valid. The time zone to associate with the LocalDateTime comes from the timeZone property of the JSCalendar object (see Section 4.7.1). If no time zone is specified, the LocalDateTime is floating. Floating date-times are not tied to any specific time zone. Instead, they occur in each time zone at the given wall-clock time (as opposed to the same instant point in time).¶
A time zone may have a period of discontinuity, for example, a change from standard time to daylight savings time. When converting local date-times that fall in the discontinuity to UTC, the offset before the transition MUST be used.¶
For example, in the America/Los_Angeles time zone, the date-time 2020-11-01T01:30:00 occurs twice: before the daylight savings time (DST) transition with a UTC offset of -07:00 and again after the transition with an offset of -08:00. When converting to UTC, we therefore use the offset before the transition (-07:00), so it becomes 2020-11-01T08:30:00Z.¶
Similarly, in the Australia/Melbourne time zone, the date-time 2020-10-04T02:30:00 does not exist; the clocks are moved forward one hour for DST on that day at 02:00. However, such a value may appear during calculations (see duration semantics in Section 1.4.6) or due to a change in time zone rules (so it was valid when the event was first created). Again, it is interpreted as though the offset before the transition is in effect (+10:00); therefore, when converted to UTC, we get 2020-10-03T16:30:00Z.¶
Where Duration is given as a type, it means a length of time represented by a subset of the ISO 8601 duration format, as specified by the following ABNF [RFC5234]:¶
dur-secfrac = "." 1*DIGIT
dur-second = 1*DIGIT [dur-secfrac] "S"
dur-minute = 1*DIGIT "M" [dur-second]
dur-hour = 1*DIGIT "H" [dur-minute]
dur-time = "T" (dur-hour / dur-minute / dur-second)
dur-day = 1*DIGIT "D"
dur-week = 1*DIGIT "W"
dur-cal = (dur-week [dur-day] / dur-day)
duration = "P" (dur-cal [dur-time] / dur-time)
¶
In addition, the duration MUST NOT include fractional second values unless the fraction is non-zero. Fractional second values MUST NOT have trailing zeros to ensure there is only a single representation for each duration.¶
A duration specifies an abstract number of weeks, days, hours, minutes, and/or seconds. A duration specified using weeks or days does not always correspond to an exact multiple of 24 hours. The number of hours/minutes/seconds may vary if it overlaps a period of discontinuity in the event's time zone, for example, a change from standard time to daylight savings time. Leap seconds MUST NOT be considered when adding or subtracting a duration to/from a LocalDateTime.¶
To add a duration to a LocalDateTime:¶
To subtract a duration from a LocalDateTime, the steps apply in reverse:¶
These semantics match the iCalendar DURATION value type ([RFC5545], Section 3.3.6).¶
A SignedDuration represents a length of time that may be positive or negative and is typically used to express the offset of a point in time relative to an associated time. It is represented as a Duration, optionally preceded by a sign character. It is specified by the following ABNF:¶
signed-duration = ["+" / "-"] duration¶
A negative sign indicates a point in time at or before the associated time; a positive or no sign indicates a time at or after the associated time.¶
Where TimeZoneId is given as a data type, it means a String that is a time zone name in the IANA Time Zone Database [TZDB]. The zone rules of the respective IANA time zone records apply.¶
A PatchObject is of type String[*] and represents an unordered set of patches on a JSON object. Each key is a path represented in a subset of the JSON Pointer format [RFC6901]. The paths have an implicit leading /, so each key is prefixed with / before applying the JSON Pointer evaluation algorithm.¶
A patch within a PatchObject is only valid if all of the following conditions apply:¶
alerts/1/offset and alerts.¶
The value associated with each pointer determines how to apply that patch:¶
A PatchObject does not define its own @type property (see Section 1.3.3). An @type property in a patch MUST be handled as any other patched property value.¶
Implementations MUST reject a PatchObject in its entirety if any of its patches are invalid. Implementations MUST NOT apply partial patches.¶
The PatchObject format is used to significantly reduce file size and duplicated content when specifying variations to a common object, such as with recurring events or when translating the data into multiple languages. It can also better preserve semantic intent if only the properties that should differ between the two objects are patched. For example, if one person is not going to a particular instance of a regularly scheduled event, in iCalendar, you would have to duplicate the entire event in the override. In JSCalendar, this is a small patch to show the difference. As only this property is patched, if the location of the event is changed, the occurrence will automatically still inherit this.¶
A Relation object defines the relation to other objects, using a possibly empty set of relation types. The object that defines this relation is the linking object, while the other object is the linked object. A Relation object has the following properties:¶
String (mandatory)Relation, if set.¶
String[Boolean] (optional, default: empty Object)This describes how the linked object is related to the linking object. The relation is defined as a set of relation types. Keys in the set MUST be one of the following values, specified in the property definition where the Relation object is used, a value registered in the IANA "JSCalendar Enum Values" registry, or a vendor-specific value (see Section 3.3):¶
first:next:child:parent:The value for each key in the map MUST be true. The empty Object value represents a "parent" relation, unless otherwise specified for the object type.¶
A Link object represents an external resource associated with the linking object. It has the following properties:¶
String (mandatory)Link, if set.¶
String (mandatory)This is a URI[RFC3986] from which the resource may be fetched.¶
This MAY be a data: URL [RFC2397], but it is recommended that the file be hosted on a server to avoid embedding arbitrarily large data in JSCalendar object instances.¶
String (optional)UnsignedInt (optional)String (optional)String[Boolean] (optional)This is a set of intended purposes of a link to an image. The keys MUST be one of the following values, another value registered in the IANA "JSCalendar Enum Values" registry, or a vendor-specific value (see Section 3.3):¶
badge:graphic:fullsize:thumbnail:fullsize to be used when space for the image is constrained¶
The value for each key in the map MUST be true. If this property is set, then the rel property MUST be set to icon.¶
String (optional)This section describes the calendar object types specified by JSCalendar.¶
Media type: application/jscalendar+json;type=event¶
An Event represents a scheduled amount of time on a calendar, typically a meeting, appointment, reminder, or anniversary. It is required to start at a certain point in time and typically has a non-zero duration. Multiple participants may partake in the event.¶
The @type (Section 1.3.3) property value MUST be Event.¶
Media type: application/jscalendar+json;type=task¶
A Task represents an action item, assignment, to-do item, or work item. It may start and be due at certain points in time, take some estimated time to complete, and recur, none of which is required.¶
The @type (Section 1.3.3) property value MUST be Task.¶
Media type: application/jscalendar+json;type=group¶
A Group is a collection of Event (Section 2.1) and/or Task (Section 2.2) objects. Typically, objects are grouped by topic (e.g., by keywords) or calendar membership.¶
The @type (Section 1.3.3) property value MUST be Group.¶
A JSCalendar object is a JSON object [RFC8259], which MUST be valid I-JSON (a stricter subset of JSON) [RFC7493]. Property names and values are case sensitive.¶
The object has a collection of properties, as specified in the following sections. Properties are specified as being either mandatory or optional. Optional properties may have a default value if explicitly specified in the property definition.¶
JSCalendar objects MUST name their type in the @type property if not explicitly specified otherwise for the respective object type. A notable exception to this rule is the PatchObject (Section 1.4.9).¶
JSCalendar aims to provide unambiguous definitions for value types and properties but does not define a general normalization or equivalence method for JSCalendar objects and types. This is because the notion of equivalence might range from byte-level equivalence to semantic equivalence, depending on the respective use case. Normalization of JSCalendar objects is hindered because of the following reasons:¶
Considering this, the definition of equivalence and normalization is left to client and server implementations and to be negotiated by a calendar exchange protocol or defined elsewhere.¶
Vendors MAY add additional properties to the calendar object to support their custom features. To avoid conflict, the names of these properties MUST be prefixed by a domain name controlled by the vendor followed by a colon, e.g., example.com:customprop. If the value is a new JSCalendar object, it either MUST include an @type property, or it MUST explicitly be specified to not require a type designator. The type name MUST be prefixed with a domain name controlled by the vendor.¶
Some JSCalendar properties allow vendor-specific value extensions. Such vendor-specific values MUST be prefixed by a domain name controlled by the vendor followed by a colon, e.g., example.com:customrel.¶
Vendors are strongly encouraged to register any new property values or extensions that are useful to other systems as well, rather than use a vendor-specific prefix.¶
This section describes the properties that are common to the various JSCalendar object types. Specific JSCalendar object types may only support a subset of these properties. The object type definitions in Section 5 describe the set of supported properties per type.¶
Type: String (mandatory)¶
This is a globally unique identifier used to associate objects representing the same event, task, group, or other object across different systems, calendars, and views. For recurring events and tasks, the UID is associated with the base object and therefore is the same for all occurrences; the combination of the UID with a recurrenceId identifies a particular instance.¶
The generator of the identifier MUST guarantee that the identifier is unique. [RFC4122] describes a range of established algorithms to generate universally unique identifiers (UUIDs). UUID version 4, described in Section 4.4 of [RFC4122], is RECOMMENDED.¶
For compatibility with UIDs [RFC5545], implementations MUST be able to receive and persist values of at least 255 octets for this property, but they MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.¶
Type: String (optional)¶
This is the identifier for the product that last updated the JSCalendar object. This should be set whenever the data in the object is modified (i.e., whenever the updated property is set).¶
The vendor of the implementation MUST ensure that this is a globally unique identifier, using some technique such as a Formal Public Identifier (FPI) value, as defined in [ISO.9070.1991].¶
This property SHOULD NOT be used to alter the interpretation of a JSCalendar object beyond the semantics specified in this document. For example, it is not to be used to further the understanding of nonstandard properties, a practice that is known to cause long-term interoperability problems.¶
Type: UTCDateTime (optional)¶
This is the date and time this object was initially created.¶
Type: UTCDateTime (mandatory)¶
This is the date and time the data in this object was last modified (or its creation date/time if not modified since).¶
Type: UnsignedInt (optional, default: 0)¶
Initially zero, this MUST be incremented by one every time a change is made to the object, except if the change only modifies the participants property (see Section 4.4.5).¶
This is used as part of the iCalendar Transport-independent Interoperability Protocol (iTIP) [RFC5546] to know which version of the object a scheduling message relates to.¶
Type: String (optional, default: empty String)¶
This is a short summary of the object.¶
Type: String (optional, default: empty String)¶
This is a longer-form text description of the object. The content is formatted according to the descriptionContentType property.¶
Type: String (optional, default: text/plain)¶
This describes the media type [RFC6838] of the contents of the description property. Media types MUST be subtypes of type text and SHOULD be text/plain or text/html [MEDIATYPES]. They MAY include parameters, and the charset parameter value MUST be utf-8, if specified.¶
Type: Boolean (optional, default: false)¶
This indicates that the time is not important to display to the user when rendering this calendar object. An example of this is an event that conceptually occurs all day or across multiple days, such as "New Year's Day" or "Italy Vacation". While the time component is important for free-busy calculations and checking for scheduling clashes, calendars may choose to omit displaying it and/or display the object separately to other objects to enhance the user's view of their schedule.¶
Such events are also commonly known as "all-day" events.¶
Type: Id[Location] (optional)¶
This is a map of location ids to Location objects, representing locations associated with the object.¶
A Location object has the following properties. It MUST have at least one property other than the @type property.¶
String (mandatory)Location, if set.¶
String (optional)String (optional)String (optional)description property. Its requirements are specified in Section 4.2.3. If this property is set, then the description property MUST be set.¶
String[Boolean] (optional)String (optional)geo: URI [RFC5870] for the location.¶
Id[Link] (optional)Type: String (optional)¶
This indicates which of the multiple entries in the locations property can be considered the main location for the event or task. A client implementation MAY choose to display this location more prominently. The main location is undefined if this property is not set or if its value does not match the key of any Location object.¶
Type: Id[VirtualLocation] (optional)¶
This is a map of virtual location ids to VirtualLocation objects, representing virtual locations, such as video conferences or chat rooms, associated with the object.¶
A VirtualLocation object has the following properties.¶
String (mandatory)VirtualLocation, if set.¶
String (optional, default: empty String)String (optional)String (optional)description property. Its requirements are specified in Section 4.2.3. If this property is set, then the description property MUST be set.¶
String (mandatory)This is a URI[RFC3986] that represents how to connect to this virtual location.¶
This may be a telephone number (represented using the tel: scheme, e.g., tel:+1-555-555-5555) for a teleconference, a web address for online chat, or any custom URI.¶
String[Boolean] (optional)A set of features supported by this virtual location. The set is represented as a map, with the keys being the feature. The value for each key in the map MUST be true.¶
The feature MUST be one of the following values, another value registered in the IANA "JSCalendar Enum Values" registry, or a vendor-specific value (see Section 3.3). Any value the client or server doesn't understand should be treated the same as if this feature is omitted.¶
Type: Id[Link] (optional)¶
This is a map of link ids to Link objects, representing external resources associated with the object.¶
Links with a rel of enclosure MUST be considered by the client to be attachments for download.¶
Links with a rel of describedby MUST be considered by the client to be alternative representations of the description.¶
Links with a rel of icon MUST be considered by the client to be images that it may use when presenting the calendar data to a user. The display property may be set to indicate the purpose of this image.¶
Type: String (optional)¶
This is the language tag, as defined in [RFC5646], that best describes the locale used for the text in the calendar object, if known.¶
Type: String[Boolean] (optional)¶
This is a set of keywords or tags that relate to the object. The set is represented as a map, with the keys being the keywords. The value for each key in the map MUST be true.¶
Type: String[Boolean] (optional)¶
This is a set of categories that relate to the calendar object. The set is represented as a map, with the keys being the categories specified as URIs. The value for each key in the map MUST be true.¶
In contrast to keywords, categories are typically structured. For example, a vendor owning the domain example.com might define the categories http://example.com/categories/sports/american-football and http://example.com/categories/music/r-b.¶
Type: String (optional)¶
This is a color clients MAY use when displaying this calendar object. The value is a color name taken from the set of names defined in Section 4.3 of CSS Color Module Level 3 [COLORS] or an RGB value in hexadecimal notation, as defined in Section 4.2.1 of CSS Color Module Level 3.¶
Some events and tasks occur at regular or irregular intervals. Rather than having to copy the data for every occurrence, there can be a base event with a rule to generate recurrences and/or overrides that add extra dates or exceptions to the rule.¶
The recurrence set is the complete set of instances for an object. It is generated by considering the following properties in order, all of which are optional:¶
recurrenceRule property (Section 4.3.3) generates a set of extra date-times on which the object occurs.¶
recurrenceOverrides property (Section 4.3.4) defines date-times that are added or excluded to form the final set. (This property may also contain changes to the object to apply to particular instances.)¶
Type: LocalDateTime (optional)¶
If present, this JSCalendar object represents one occurrence of a recurring JSCalendar object. If present, the recurrenceRule and recurrenceOverrides properties MUST NOT be present.¶
The value is a date-time either produced by the recurrenceRule of the base event or added as a key to the recurrenceOverrides property of the base event.¶
Type: TimeZoneId|null (optional, default: null)¶
Identifies the time zone of the main JSCalendar object, of which this JSCalendar object is a recurrence instance. It MUST NOT be set if the recurrenceId property is not set.¶
Type: RecurrenceRule (optional)¶
This a recurrence rule (a repeating pattern) for recurring calendar objects.¶
An Event recurs by applying the recurrence rule to the start date-time.¶
A Task recurs by applying the recurrence rule to the start date-time, if defined; otherwise, it recurs by the due date-time, if defined. If the task defines neither a start nor due date-time, it MUST NOT define a recurrenceRule property.¶
A RecurrenceRule object is a JSON object mapping of a RECUR value type in iCalendar [RFC5545] [RFC7529] and has the same semantics. It has the following properties:¶
String (mandatory)RecurrenceRule, if set.¶
String (mandatory)This is the time span covered by each iteration of this recurrence rule (see Section 4.3.3.1 for full semantics). This MUST be one of the following values:¶
This is the FREQ part from iCalendar, converted to lowercase.¶
UnsignedInt (optional, default: 1)This is the interval of iteration periods at which the recurrence repeats. If included, it MUST be an integer >= 1.¶
This is the INTERVAL part from iCalendar.¶
String (optional, default: "gregorian")This is the calendar system in which this recurrence rule operates, in lowercase. This MUST be either a CLDR-registered calendar system name [CLDR] or a vendor-specific value (see Section 3.3).¶
This is the RSCALE part from iCalendar RSCALE [RFC7529], converted to lowercase.¶
String (optional, default: "omit")This is the behavior to use when the expansion of the recurrence produces invalid dates. This property only has an effect if the frequency is "yearly" or "monthly". It MUST be one of the following values:¶
This is the SKIP part from iCalendar RSCALE [RFC7529], converted to lowercase.¶
String (optional, default: "mo")This is the day on which the week is considered to start, represented as a lowercase, abbreviated, and two-letter English day of the week. If included, it MUST be one of the following values:¶
This is the WKST part from iCalendar.¶
NDay[] (optional)These are days of the week on which to repeat. An NDay object has the following properties:¶
String (mandatory)NDay, if set.¶
String (mandatory)This is a day of the week on which to repeat; the allowed values are the same as for the firstDayOfWeek recurrenceRule property.¶
This is the day of the week of the BYDAY part in iCalendar, converted to lowercase.¶
Int (optional)If present, rather than representing every occurrence of the weekday defined in the day property, it represents only a specific instance within the recurrence period. The value can be positive or negative but MUST NOT be zero. A negative integer means the nth-last occurrence within that period (i.e., -1 is the last occurrence, -2 the one before that, etc.).¶
This is the ordinal part of the BYDAY value in iCalendar (e.g., 1 or -3).¶
Int[] (optional)These are the days of the month on which to repeat. Valid values are between 1 and the maximum number of days any month may have in the calendar given by the rscale property and the negative values of these numbers. For example, in the Gregorian calendar, valid values are 1 to 31 and -31 to -1. Negative values offset from the end of the month. The array MUST have at least one entry if included.¶
This is the BYMONTHDAY part in iCalendar.¶
String[] (optional)These are the months in which to repeat. Each entry is a string representation of a number, starting from "1" for the first month in the calendar (e.g., "1" means January with the Gregorian calendar), with an optional "L" suffix (see [RFC7529]) for leap months (this MUST be uppercase, e.g., "3L"). The array MUST have at least one entry if included.¶
This is the BYMONTH part from iCalendar.¶
Int[] (optional)These are the days of the year on which to repeat. Valid values are between 1 and the maximum number of days any year may have in the calendar given by the rscale property and the negative values of these numbers. For example, in the Gregorian calendar, valid values are 1 to 366 and -366 to -1. Negative values offset from the end of the year. The array MUST have at least one entry if included.¶
This is the BYYEARDAY part from iCalendar.¶
Int[] (optional)These are the weeks of the year in which to repeat. Valid values are between 1 and the maximum number of weeks any year may have in the calendar given by the rscale property and the negative values of these numbers. For example, in the Gregorian calendar, valid values are 1 to 53 and -53 to -1. The array MUST have at least one entry if included.¶
This is the BYWEEKNO part from iCalendar.¶
UnsignedInt[] (optional)These are the hours of the day in which to repeat. Valid values are 0 to 23. The array MUST have at least one entry if included. This is the BYHOUR part from iCalendar.¶
UnsignedInt[] (optional)These are the minutes of the hour in which to repeat. Valid values are 0 to 59. The array MUST have at least one entry if included.¶
This is the BYMINUTE part from iCalendar.¶
UnsignedInt[] (optional)These are the seconds of the minute in which to repeat. Valid values are 0 to 60. The array MUST have at least one entry if included.¶
This is the BYSECOND part from iCalendar.¶
Int[] (optional)UnsignedInt (optional)These are the number of occurrences at which to range-bound the recurrence. This MUST NOT be included if an until property is specified.¶
This is the COUNT part from iCalendar.¶
LocalDateTime (optional)These are the date-time at which to finish recurring. The last occurrence is on or before this date-time. This MUST NOT be included if a count property is specified. Note that if not specified otherwise for a specific JSCalendar object, this date is to be interpreted in the time zone specified in the JSCalendar object's timeZone property.¶
This is the UNTIL part from iCalendar.¶
A recurrence rule specifies a set of date-times for recurring calendar objects. A recurrence rule has the following semantics. Note that wherever "year", "month", or "day of month" is used, this is within the calendar system given by the rscale property, which defaults to "gregorian" if omitted.¶
A set of candidates is generated. This is every second within a period defined by the frequency property value:¶
yearly:every second from midnight on the first day of a year (inclusive) to midnight the first day of the following year (exclusive).¶
If skip is not "omit", the calendar system has leap months, and there is a byMonth property, generate candidates for the leap months, even if they don't occur in this year.¶
If skip is not "omit" and there is a byMonthDay property, presume each month has the maximum number of days any month may have in this calendar system when generating candidates, even if it's more than this month actually has.¶
monthly:every second from midnight on the first day of a month (inclusive) to midnight on the first of the following month (exclusive).¶
If skip is not "omit" and there is a byMonthDay property, presume the month has the maximum number of days any month may have in this calendar system when generating candidates, even if it's more than this month actually has.¶
weekly:firstDayOfWeek property or Monday if omitted) to midnight seven days later (exclusive).¶
daily:hourly:minutely:secondly:Each date-time candidate is compared against all of the byX properties of the rule except bySetPosition. If any property in the rule does not match the date-time, the date-time is eliminated. Each byX property is an array; the date-time matches the property if it matches any of the values in the array. The properties have the following semantics:¶
The date-time is in the nth week of the year. Negative numbers mean the nth last week of the year. This corresponds to weeks according to week numbering, as defined in ISO.8601.2004, with a week defined as a seven-day period, starting on the firstDayOfWeek property value or Monday if omitted. Week number one of the calendar year is the first week that contains at least four days in that calendar year.¶
If the date-time is not valid (this may happen when generating candidates with a skip property in effect), it is always eliminated by this property.¶
The date-time is on the nth day of year. Negative numbers mean the nth last day of the year.¶
If the date-time is not valid (this may happen when generating candidates with a skip property in effect), it is always eliminated by this property.¶
If a skip property is defined and is not "omit", there may be candidates that do not correspond to valid dates (e.g., February 31st in the Gregorian calendar). In this case, the properties MUST be considered in the order above, and:¶
bySetPosition property is included, this is now applied to the ordered list of remaining dates. This property specifies the indexes of date-times to keep; all others should be eliminated. Negative numbers are indexed from the end of the list, with -1 being the last item, -2 the second from last, etc.¶
skip property is included and is not "omit", eliminate any date-times that have already been produced by previous iterations of the algorithm. (This is not possible if skip is "omit".)¶
When determining the set of occurrence dates for an event or task, the following extra rules must be applied:¶
start date-time for events
or the start or due date-time for tasks) is always the first occurrence in the
expansion (and is counted if the recurrence is limited by a count property), even if it would
normally not match the rule.¶
The following properties MUST be implicitly added to the rule under the given conditions:¶
secondly and there is no bySecond property, add a bySecond
property with the sole value being the seconds value of the initial date-time.¶
secondly or minutely and there is no byMinute
property, add a byMinute property with the sole value being the minutes value of the initial
date-time.¶
secondly, minutely, or hourly and there is
no byHour property, add a byHour property with the sole value being the hours value of the
initial date-time.¶
weekly and there is no byDay property, add a byDay property with
the sole value being the day of the week of the initial date-time.¶
monthly and there is no byDay property and no byMonthDay
property, add a byMonthDay property with the sole value being the day of the month of the
initial date-time.¶
If frequency is yearly and there is no byYearDay property:¶
byMonth or byWeekNo properties, and either there is a byMonthDay property or there is no byDay property, add a byMonth property with the sole value being the month of the initial date-time.¶
byMonthDay, byWeekNo, or byDay properties, add a byMonthDay property with the sole value being the day of the month of the initial date-time.¶
byWeekNo property and no byMonthDay or byDay properties, add a byDay property with the sole value being the day of the week of the initial date-time.¶
Type: LocalDateTime[PatchObject] (optional)¶
Maps recurrence ids (the date-time produced by the recurrence rule) to the overridden properties of the recurrence instance.¶
If the recurrence id does not match a date-time from the recurrence rule (or no rule is specified), it is to be treated as an additional occurrence (like an RDATE from iCalendar). The patch object may often be empty in this case.¶
If the occurrence generated by the recurrence id shall be omitted from the final set of recurrences (like an EXDATE from iCalendar), then the patch object MUST be a JSON object with a single member. The member name MUST be "excluded", the member value MUST be true. The JSON object MUST NOT contain any other members.¶
By default, an occurrence inherits all properties from the main object except the start (or due) date-time, which is shifted to match the recurrence id LocalDateTime. However, individual properties of the occurrence can be modified by a patch or multiple patches. It is valid to patch the start property value, and this patch takes precedence over the value generated from the recurrence id. Both the recurrence id as well as the patched start date-time may occur before the original JSCalendar object's start or due date.¶
A pointer in the PatchObject MUST be ignored if it starts with one of the following prefixes:¶
Type: Id[Alert] (optional)¶
This is a map of alert ids to Alert objects, representing alerts/reminders to display or send to the user for this calendar object.¶
An Alert object has the following properties:¶
String (mandatory)Alert, if set.¶
OffsetTrigger|AbsoluteTrigger|UnknownTrigger (mandatory, defaultType: OffsetTrigger)This defines when to trigger the alert. New types may be defined in future documents.¶
An OffsetTrigger object has the following properties:¶
String (mandatory)OffsetTrigger, if set.¶
SignedDuration (mandatory)relativeTo property of the alert. Negative durations signify alerts before the time property; positive durations signify alerts after the time property.¶
String (optional, default: start )This specifies the time property that the alert offset is relative to. The value MUST be one of the following:¶
An AbsoluteTrigger object has the following properties:¶
String (mandatory)AbsoluteTrigger.¶
UTCDateTime (mandatory)An UnknownTrigger object is an object that contains an @type property whose value is not recognized (i.e., not OffsetTrigger or AbsoluteTrigger ) plus zero or more other properties. This is for compatibility with client extensions and future specifications. Implementations SHOULD NOT trigger for trigger types they do not understand but MUST preserve them.¶
UTCDateTime (optional)This records when an alert was last acknowledged. This is set when the user has dismissed the alert; other clients that sync this property SHOULD automatically dismiss or suppress duplicate alerts (alerts with the same alert id that triggered on or before this date-time).¶
For a recurring calendar object, setting the acknowledged property MUST NOT add a new override to the recurrenceOverrides property. If the alert is not already overridden, the acknowledged property MUST be set on the alert in the base event/task.¶
Certain kinds of alert action may not provide feedback as to when the user sees them, for example, email-based alerts. For those kinds of alerts, this property MUST be set immediately when the alert is triggered and the action is successfully carried out.¶
String[Relation] (optional)This relates this alert to other alerts in the same JSCalendar object. In addition to the relation values defined in Section 1.4.10, the following key is allowed:¶
snooze:If the user wishes to snooze an alert, the application MUST create an alert to trigger after snoozing. This new snooze alert MUST set a "snooze" relation to the identifier of the original alert.¶
String (optional, default: display )This describes how to alert the user.¶
The value MUST be at most one of the following values, a value registered in the IANA "JSCalendar Enum Values" registry, or a vendor-specific value (see Section 3.3):¶
Type: String[PatchObject] (optional)¶
A map where each key is a language tag [RFC5646], and the corresponding value is a set of patches to apply to the calendar object in order to localize it into that locale.¶
See the description of PatchObject (Section 1.4.9) for the structure of the PatchObject. The patches are applied to the top-level calendar object. In addition, the locale property of the patched object is set to the language tag. All pointers for patches MUST end with one of the following suffixes; any patch that does not follow this MUST be ignored unless otherwise specified in a future RFC:¶
A patch MUST NOT have the prefix recurrenceOverrides ; any localization of the override MUST be a patch to the localizations property inside the override instead. For example, a patch to locations/abcd1234/title is permissible, but a patch to uid or recurrenceOverrides/2020-01-05T14:00:00/title is not.¶
Note that this specification does not define how to maintain validity of localized content. For example, a client application changing a JSCalendar object's title property might also need to update any localizations of this property. Client implementations SHOULD provide the means to manage localizations, but how to achieve this is specific to the application's workflow and requirements.¶
In addition to the common JSCalendar object properties (Section 4), an Event has the following properties:¶
Type: LocalDateTime (mandatory)¶
This is the date/time the event starts in the event's time zone (as specified in the timeZone property, see Section 4.7.1).¶
Type: Duration (optional, default: PT0S)¶
This is the zero or positive duration of the event in the event's start time zone. The end time of an event can be found by adding the duration to the event's start time.¶
Type: TimeZoneId (optional)¶
This identifies the time zone in which this event ends, for cases where the start and time zones of the event differ (e.g., a transcontinental flight). If this property is not set, then the event starts and ends in the same time zone. This property MUST NOT be set if the timeZone property value is null or not set.¶
Type: String (optional, default: confirmed)¶
This is the scheduling status ( Section 4.4) of an Event. If set, it MUST be one of the following values, another value registered in the IANA "JSCalendar Enum Values" registry, or a vendor-specific value (see Section 3.3):¶
In addition to the common JSCalendar object properties (Section 4), a Task has the following properties:¶
Type: LocalDateTime (optional)¶
This is the date/time the task is due in the task's time zone. If the timeZone property is set, then at least one of the due and start properties MUST be set¶
Type: LocalDateTime (optional)¶
This the date/time the task should start in the task's time zone. If the timeZone property is set, then at least one of the due and start properties MUST be set¶
Type: Duration (optional)¶
This specifies the estimated positive duration of time the task takes to complete.¶
Type: UnsignedInt (optional)¶
This represents the percent completion of the task overall. The property value MUST be a positive integer between 0 and 100.¶
Type: String (optional)¶
This defines the progress of this task. If omitted, the default progress ( Section 4.4) of a Task is defined as follows (in order of evaluation):¶
completed:progress property value of all participants is completed¶
failed:progress property value of a participant is failed¶
in-process:progress property value of a participant is in-process¶
needs-action:If set, it MUST be one of the following values, another value registered in the IANA "JSCalendar Enum Values" registry, or a vendor-specific value (see Section 3.3):¶
Group supports the following common JSCalendar properties (Section 4) :¶
In addition, the following Group-specific properties are supported:¶
The following examples illustrate several aspects of the JSCalendar data model and format. The examples may omit mandatory or additional properties, which is indicated by a placeholder property with key .... While most of the examples use calendar event objects, they are also illustrative for tasks.¶
This example illustrates a simple one-time event. It specifies a one-time event that begins on January 15, 2020 at 1 pm New York local time and ends after 1 hour.¶
{
"@type": "Event",
"uid": "a8df6573-0474-496d-8496-033ad45d7fea",
"updated": "2020-01-02T18:23:04Z",
"title": "Some event",
"start": "2020-01-15T13:00:00",
"timeZone": "America/New_York",
"duration": "PT1H"
}
¶
This example illustrates a simple task for a plain to-do item.¶
{
"@type": "Task",
"uid": "2a358cee-6489-4f14-a57f-c104db4dc2f2",
"updated": "2020-01-09T14:32:01Z",
"title": "Do something"
}
¶
This example illustrates a simple calendar object group that contains an event and a task.¶
{
"@type": "Group",
"uid": "bf0ac22b-4989-4caf-9ebd-54301b4ee51a",
"updated": "2020-01-15T18:00:00Z",
"title": "A simple group",
"entries": [{
"@type": "Event",
"uid": "a8df6573-0474-496d-8496-033ad45d7fea",
"updated": "2020-01-02T18:23:04Z",
"title": "Some event",
"start": "2020-01-15T13:00:00",
"timeZone": "America/New_York",
"duration": "PT1H"
},
{
"@type": "Task",
"uid": "2a358cee-6489-4f14-a57f-c104db4dc2f2",
"updated": "2020-01-09T14:32:01Z",
"title": "Do something"
}]
}
¶
This example illustrates an event for an international holiday. It specifies an all-day event on April 1 that occurs every year since the year 1900.¶
{
"...": "",
"title": "April Fool's Day",
"showWithoutTime": true,
"start": "1900-04-01T00:00:00",
"duration": "P1D",
"recurrenceRule": {
"frequency": "yearly"
}
}
¶
This example illustrates a task with a due date. It is a reminder to buy groceries before 6 pm Vienna local time on January 19, 2020. The calendar user expects to need 1 hour for shopping.¶
{
"...": "",
"title": "Buy groceries",
"due": "2020-01-19T18:00:00",
"timeZone": "Europe/Vienna",
"estimatedDuration": "PT1H"
}
¶
This example illustrates the use of end time zones by use of an international flight. The flight starts on April 1, 2020 at 9 am in Berlin local time. The duration of the flight is scheduled at 10 hours 30 minutes. The time at the flight's destination is in the same time zone as Tokyo. Calendar clients could use the end time zone to display the arrival time in Tokyo local time and highlight the time zone difference of the flight. The location names can serve as input for navigation systems. The mainLocationId property indicates the start location.¶
{
"...": "",
"title": "Flight XY51 to Tokyo",
"start": "2020-04-01T09:00:00",
"timeZone": "Europe/Berlin",
"endTimeZone": "Asia/Tokyo",
"duration": "PT10H30M",
"mainLocationId": "1",
"locations": {
"1": {
"name": "Frankfurt Airport (FRA)"
},
"2": {
"name": "Narita International Airport (NRT)"
}
}
}
¶
This example illustrates the use of floating time. Since January 1, 2020, a calendar user blocks 30 minutes every day to practice yoga at 7 am local time in whatever time zone the user is located on that date.¶
{
"...": "",
"title": "Yoga",
"start": "2020-01-01T07:00:00",
"duration": "PT30M",
"recurrenceRule": {
"frequency": "daily"
}
}
¶
This example illustrates an event that happens at both a physical and a virtual location. Fans can see a live concert on premises or online. The event title and descriptions are localized.¶
{
"...": "",
"title": "Live from Music Bowl: The Band",
"description": "Go see the biggest music event ever!",
"locale": "en",
"start": "2020-07-04T17:00:00",
"timeZone": "America/New_York",
"duration": "PT3H",
"locations": {
"c0503d30-8c50-4372-87b5-7657e8e0fedd": {
"name": "The Music Bowl",
"description": "Music Bowl, Central Park, New York",
"coordinates": "geo:40.7829,-73.9654"
}
},
"virtualLocations": {
"vloc1": {
"name": "Free live Stream from Music Bowl",
"uri": "https://stream.example.com/the_band_2020"
}
},
"localizations": {
"de": {
"title": "Live von der Music Bowl: The Band!",
"description": "Schau dir das größte Musikereignis an!",
"virtualLocations/vloc1/name":
"Gratis Live-Stream aus der Music Bowl"
}
}
}
¶
This example illustrates the use of recurrence overrides. A math course at a university is held for the first time on January 8, 2020 at 9 am London time and occurs every week until June 24, 2020. Each lecture lasts for one hour and 30 minutes and is located at the Mathematics department. This event has exceptional occurrences: at the last occurrence of the course is an exam, which lasts for 2 hours and starts at 10 am. Also, the location of the exam differs from the usual location. On April 1, no course is held. On January 7 at 2 pm, there is an optional introduction course, which occurs before the first regular lecture.¶
{
"...": "",
"title": "Calculus I",
"start": "2020-01-08T09:00:00",
"timeZone": "Europe/London",
"duration": "PT1H30M",
"locations": {
"mlab": {
"title": "Math lab room 1",
"description": "Math Lab I, Department of Mathematics"
}
},
"recurrenceRule": {
"frequency": "weekly",
"until": "2020-06-24T09:00:00"
},
"recurrenceOverrides": {
"2020-01-07T14:00:00": {
"title": "Introduction to Calculus I (optional)"
},
"2020-04-01T09:00:00": {
"excluded": true
},
"2020-06-25T09:00:00": {
"title": "Calculus I Exam",
"start": "2020-06-25T10:00:00",
"duration": "PT2H",
"locations": {
"auditorium": {
"title": "Big Auditorium",
"description": "Big Auditorium, Other Road"
}
}
}
}
}
¶
This example illustrates scheduled events. A team meeting occurs every week since January 8, 2020 at 9 am Johannesburg time. The event owner also chairs the event. Participants meet in a virtual meeting room. An attendee has accepted the invitation, but, on March 4, 2020, he is unavailable and declined participation for this occurrence.¶
{
"...": "",
"title": "FooBar team meeting",
"start": "2020-01-08T09:00:00",
"timeZone": "Africa/Johannesburg",
"duration": "PT1H",
"virtualLocations": {
"0": {
"name": "ChatMe meeting room",
"uri": "https://chatme.example.com?id=1234567&pw=a8a24627b63d"
}
},
"recurrenceRule": {
"frequency": "weekly"
},
"organizerCalendarAddress":
"mailto:f245f875-7f63-4a5e-a2c8@schedule.example.com",
"participants": {
"dG9tQGZvb2Jhci5xlLmNvbQ": {
"name": "Tom Tool",
"email": "tom@foobar.example.com",
"calendarAddress": "mailto:tom@calendar.example.com",
"participationStatus": "accepted",
"roles": {
"attendee": true
}
},
"em9lQGZvb2GFtcGxlLmNvbQ": {
"name": "Zoe Zelda",
"calendarAddress": mailto:zoe@foobar.example.com",
"participationStatus": "accepted",
"roles": {
"owner": true,
"attendee": true,
"chair": true
}
}
},
"recurrenceOverrides": {
"2020-03-04T09:00:00": {
"participants/dG9tQGZvb2Jhci5xlLmNvbQ/participationStatus":
"declined"
}
}
}
¶
Calendaring and scheduling information is very privacy sensitive. It can reveal the social network of a user, location information of this user and those in their social network, identity and credentials information, and patterns of behavior of the user in both the physical and cyber realm. Additionally, calendar events and tasks can influence the physical location of a user or their cyber behavior within a known time window. Its transmission and storage must be done carefully to protect it from possible threats, such as eavesdropping, replay, message insertion, deletion, modification, and on-path attacks.¶
The data being stored and transmitted may be used in systems with real-world consequences. For example, a home automation system may turn an alarm on and off or a coworking space may charge money to the organizer of an event that books one of their meeting rooms. Such systems must be careful to authenticate all data they receive to prevent them from being subverted and ensure the change comes from an authorized entity.¶
This document only defines the data format; such considerations are primarily the concern of the API or method of storage and transmission of such files.¶
A recurrence rule may produce infinite occurrences of an event. Implementations MUST handle expansions carefully to prevent accidental or deliberate resource exhaustion.¶
Conversely, a recurrence rule may be specified that does not expand to anything. It is not always possible to tell this through static analysis of the rule, so implementations MUST be careful to avoid getting stuck in infinite loops or otherwise exhausting resources while searching for the next occurrence.¶
Events recur in the event's time zone. If the user is in a different time zone, daylight saving transitions may cause an event that normally occurs at, for example, 9 am to suddenly shift an hour earlier. This may be used in an attempt to cause a participant to miss an important meeting. User agents must be careful to translate date-times correctly between time zones and may wish to call out unexpected changes in the time of a recurring event.¶
The security considerations of [RFC8259] apply to the use of JSON as the data interchange format.¶
As for any serialization format, parsers need to thoroughly check the syntax of the supplied data. JSON uses opening and closing tags for several types and structures, and it is possible that the end of the supplied data will be reached when scanning for a matching closing tag; this is an error condition, and implementations need to stop scanning at the end of the supplied data.¶
JSON also uses a string encoding with some escape sequences to encode special characters within a string. Care is needed when processing these escape sequences to ensure that they are fully formed before the special processing is triggered, with special care taken when the escape sequences appear adjacent to other (non-escaped) special characters or adjacent to the end of data (as in the previous paragraph).¶
If parsing JSON into a non-textual structured data format, implementations may need to allocate storage to hold JSON string elements. Since JSON does not use explicit string lengths, the risk of denial of service due to resource exhaustion is small, but implementations may still wish to place limits on the size of allocations they are willing to make in any given context, to avoid untrusted data causing excessive memory allocation.¶
Several JSCalendar properties contain URIs as values, and processing these properties requires extra care. Section 7 of [RFC3986] discusses security risks related to URIs.¶
Fetching remote resources carries inherent risks. Connections must only be allowed on well-known ports, using allowed protocols (generally, just HTTP/HTTPS on their default ports). The URL must be resolved externally and not allowed to access internal resources. Connecting to an external source reveals IP (and therefore often location) information.¶
A maliciously constructed JSCalendar object may contain a very large number of URIs. In the case of published calendars with a large number of subscribers, such objects could be widely distributed. Implementations should be careful to limit the automatic fetching of linked resources to reduce the risk of this being an amplification vector for a denial-of-service attack.¶
Calendar systems may receive JSCalendar files from untrusted sources, in particular, as attachments to emails. This can be a vector for an attacker to inject spam into a user's calendar. This may confuse, annoy, and mislead users or overwhelm their calendar with bogus events, preventing them from seeing legitimate ones.¶
Heuristic, statistical, or machine-learning-based filters can be effective in filtering out spam. Authentication mechanisms, such as DomainKeys Identified Mail (DKIM) [RFC6376], can help establish the source of messages and associate the data with existing relationships (such as an address book contact). However, misclassifications are always possible and providing a mechanism for users to quickly correct this is advised.¶
Confusable unicode characters may be used to trick a user into trusting a JSCalendar file that appears to come from a known contact but is actually from a similar-looking source controlled by an attacker.¶
It is important for calendar systems to maintain the UID of an event when updating it to avoid an unexpected duplication of events. Consumers of the data may not remove the previous version of the event if it has a different UID. This can lead to a confusing situation for the user, with many variations of the event and no indication of which one is correct. Care must be taken by consumers of the data to remove old events where possible to avoid an accidental denial-of-service attack due to the volume of data.¶
Events recur in a particular time zone. When this differs from the user's current time zone, it may unexpectedly cause an occurrence to shift in time for that user due to a daylight savings change in the event's time zone. A maliciously crafted event could attempt to confuse users with such an event to ensure a meeting is missed.¶
This section documents all significant differences from RFC 8984. Insignificant differences, such as formatting, grammar or typos are not documented.¶
All verified errata of RFC 8984 was applied to this document:¶
The following properties became obsolete:¶
This is incompatible with iCalendar, which deprecated the EXRULE property [RFC2445] (Section 4.8.5.2) in [RFC5545].¶
See Section 4.3.4 of [RFC8984].¶
This is incompatible with the following definitions of the iCalendar RRULE property [RFC5545] (Section 3.8.5.3):¶
The newly defined single-valued recurrenceRule property (Section 4.3.3) replaces it.¶
See Section 4.3.3 of [RFC8984].¶
This property was obsoleted for the following reasons:¶
See Section 4.7.2 of [RFC8984].¶
This property was obsoleted for the following reasons:¶
See Section 1.4.11 of [RFC8984].¶
These got replaced with the newly defined Event.endTimeZone property (Section 5.1.3):¶
See Section 4.2.5 of [RFC8984].¶
This is incompatible with the iCalendar PARTICIPANT component [RFC9073] (Section 7.1):¶
The description of the Event object type in Section 2.1 reflects this:¶
See Section 4.4.6 of [RFC8984].¶
No equivalent element exists in iCalendar and its current single-valued definition is likely to conflict with any related future extension of the PARTICIPANT component [RFC9073] (Section 7.1).¶
See Section 4.4.6 of [RFC8984].¶
This became obsolete for the following reasons:¶
See Section 4.4.6 of [RFC8984] and Section 5.2.6 of [RFC8984].¶
The following common use properties became reserved for JMAP for Calendars [I-D.ietf-jmap-calendars]:¶
No equivalent element exists in iCalendar and no consensus for default alarms in CalDAV and iCalendar was found at IETF as part of [RFC9074].¶
See Section 4.4.1 of [RFC8984].¶
The following common use properties became reserved for future JSCalendar extensions of Scheduling Extensions for CalDAV [RFC6638] and iTIP [RFC5546]:¶
This requires further work by IETF. For compatibility with iCalendar, the newly introduced organizerCalendarAddress property (Section 4.4.4) replaces it.¶
See Section 4.4.4 of [RFC8984].¶
This mainly is applicable in scheduling over CalDAV.¶
See Section 4.4.7 of [RFC8984].¶
No equivalent element exists in iCalendar and this property mainly is relevant in context of a combined calendaring and mail service. Note that the Participant.sentBy property does not become reserved: it is equivalent to the iCalendar SENT-BY [RFC5545] (Section 3.2.18) parameter.¶
See Section 4.4.5 of [RFC8984].¶
This requires further work by IETF. Specifically, the iTIP definitions of the REPLY method [RFC5546] (Section 3.2.3) and how to forward invitation requests (Section 4.2.8 of [RFC5546]) must be updated.¶
See Section 4.4.6 of [RFC8984].¶
This requires further work by IETF to update iTIP [RFC5546] with the PARTICIPANT component or JSCalendar. This property may later be redefined for common use.¶
See Section 4.4.6 of [RFC8984].¶
This only is applicable in scheduling over CalDAV.¶
See Section 4.4.6 of [RFC8984].¶
This only is applicable in scheduling over CalDAV.¶
See Section 4.4.6 of [RFC8984].¶
This only is applicable in scheduling over CalDAV.¶
See Section 4.4.6 of [RFC8984].¶
This requires further work by IETF. For compatibility with iCalendar, the newly introduced Participant.calendarAddress property (Section 4.4.5) replaces it.¶
See Section 4.4.6 of [RFC8984].¶
The following properties became reserved for internal use by JSCalendar:¶
This property name already was defined for internal use only in the recurrenceOverrides property, but registering it for common use had made it appear as being a regular property. Making this a reserved property is to help clarify its purpose. Section 4.3.4 has been updated accordingly.¶
See Section 4.3.4 of [RFC8984].¶
The following property definitions were updated:¶
The original definition required this property be set on every object type. The type and property notation in Section 1.3 now matches the one in JSContact, and the @type property is optional in the majority of cases.¶
The original definition instructed to set the "parent" relation on a snooze alert. It now instructs to set the newly defined "snooze" relation, for compatibility with the VALARM "SNOOZE" relationship type (Section 7 of [RFC9074].¶
See Section 4.5.1.¶
JSCalendar now supports default types for properties of type A|B. The default type of this property now is OffsetTrigger.¶
See Section 4.5.1.¶
The original definition only allowed one purpose to be set, which is incompatible with the multi-valued iCalendar DISPLAY parameter [RFC7986] (Section 6.1). It now supports setting multiple purposes.¶
See Section 1.4.11.¶
The original definition restricted the value of this property to registered link types. It now also allows extension relation types for compatibility with the LINKREL parameter [RFC9253] (Section 6.1).¶
See Section 1.4.11.¶
The original definitions required their values to identify Participant objects. This was incompatible with iCalendar when the DELEGATED-TO, DELEGATED-FROM or MEMBER parameters contained a calendar address but no ATTENDEE property with that same calendar address. The new definition now requires the property values to be calendar addresses.¶
Also, they now require the calendarAddress property to be set.¶
See Section 4.4.5.¶
The original definitions were incompatible with iCalendar: they did not require the (now reserved) sendTo property to be set, but their equivalent iCalendar parameters require an ATTENDEE property. They now require the calendarAddress property to be set.¶
See Section 4.4.5.¶
The original definition was incompatible with iCalendar:¶
See Section 4.4.5.¶
The original definition specified the empty relation to represent an unspecified relationship. It now defines the empty relation to default to "parent", unless overridden, for compatibility with the RELATED-TO property [RFC5545] (Section 3.8.4.5).¶
See Section 1.4.10.¶
The original definition defined these as optional, but this is incompatible with iCalendar: if the Task object's timeZone property is set, then it requires the DUE property [RFC5545] (Section 3.8.2.3) or DTSTART property [RFC5545] (Section 3.8.2.4) be set in the VTODO component. It now requires at least one of the "due" or "start" properties be set, if the "timeZone" property is set.¶
See Section 5.2.¶
The following new properties were defined:¶
This got introduced for better interoperatibility with iCalendar, where the VEVENT and VTODO components allow at most one LOCATION property to be present. While VLOCATION components [RFC9073] (Section 7.2) may occur multiple times, implementations need to know which Location to choose for the LOCATION property.¶
See Section 4.2.6.¶
This replaces the reserved replyTo property.¶
See Section 4.4.4.¶
This replaces the obsoleted recurrenceRules property.¶
See Section 4.3.3.¶
This replaces the obsoleted Location.relativeTo and Location.timeZone properties.¶
See Section 5.1.3.¶
This is for compatibility with the iCalendar STYLED-DESCRIPTION property [RFC9073] (Section 6.5) of the VLOCATION component.¶
See Section 4.2.5.¶
This replaces the reserved Participant.sendTo property.¶
See Section 4.4.5.¶
This is for consistency with the definition of the Location object type. The newly defined VCONFERENCE component will be allowed to contain the STYLED-DESCRIPTION property [RFC9073] (Section 6.5).¶
See Section 4.2.7.¶
The authors would like to thank the members of CalConnect for their valuable contributions. This specification originated from the work of the API technical committee of CalConnect: The Calendaring and Scheduling Consortium.¶