JSCalendar: A JSON representation of calendar data

This document defines a JSON-based format to exchange event and task objects, or groups of such objects, in electronic calendar applications and systems. It uses a data model that aims to be unambiguous, extendable and simple to process. The key design considerations for this format are as follows: The attributes of the calendar entry represented must be described as a simple key-value pair, reducing complexity of its representation. The data format should avoid all ambiguities, making it difficult to make mistakes during implementation and increasing interoperability. Most of the initial set of attributes should be taken from the iCalendar data format (, also see ), but a conversion between the data formats is not guaranteed to be completed without losing semantic meaning. Extensions, such as new properties and components, MUST NOT lead to requiring an update to this document. JSON is a text-based data interchange format as specified in . The I-JSON format defined in is a strict subset of this, adding restrictions to avoid potentially confusing scenarios (for example, it mandates that an object MUST NOT have two properties with the same key). Using JSON mostly is a pragmatic choice: its widespread use helps to speed up JSCalendar adoption and a wide range of production-ready JSON implementations allows to decrease interoperability issues.

The iCalendar data format , a widely deployed interchange format for calendaring and scheduling data, has served calendaring vendors for a long while, but contains some ambiguities and pitfalls that can not be overcome without backwards incompatible changes. For example, iCalendar defines various formats for local times, UTC time and dates, which confuses new users. Other sources for errors are the requirement for custom timezone definitions within a single calendar component, as well as the iCalendar format itself; the latter causing interoperability issues due to misuse of CR LF terminated strings, line continuations and subtle differences between iCalendar parsers. Lastly, up until recently the iCalendar format did not allow to express the difference between two calendar components, which results in verbose exchanges during scheduling. Some of these issues were addressed by the jCal format, which is a direct mapping between iCalendar and JSON. However, it did not attempt to extend or update iCalendar semantics.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in . 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. Some examples in this document contain "partial" JSON documents used for illustrative purposes. In these examples, three periods "..." are used to indicate a portion of the document that has been removed for compactness.

A JSCalendar object is a JSON object, which MUST be valid I-JSON (a stricter subset of JSON), as specified in . Property names and values are case-sensitive. The object has a collection of properties, as specified in the following sections. Unless otherwise specified, all properties are optional; omitted properties MUST be treated identically to if that property had the value of null, unless otherwise specified.

Types signatures are given for all JSON objects in this document. The following conventions are used: Boolean|String: The value is either a JSON Boolean value, or a JSON String value. Foo: Any name that is not a native JSON type means an object for which the properties (and their types) are defined elsewhere within this document. Foo[]: An array of objects of type Foo. String[Foo]: A JSON Object being used as a map (associative array), where all the values are of type Foo.

In addition to the standard JSON data types, the following data types are used in this specification:

This is a string in date-time format, with the further restrictions that any letters MUST be in upper-case, the time component MUST be included and the time MUST be in UTC. 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 OK, but 2010-10-10T10:10:10.000Z is invalid and MUST be encoded as 2010-10-10T10:10:10Z. In common notation, it should be of the form YYYY-MM-DDTHH:MM:SSZ.

This is a date-time string with no time zone/offset information. It is otherwise in the same format as UTCDate: YYYY-MM-DDTHH:MM:SS. The time zone to associate the LocalDate with comes from an associated property, or if no time zone is associated it defines floating time. Floating date-times represents all such points in time that are represented on all time-lines with the same calendar day and clock time.

A duration is represented by a subset of ISO8601 duration format, as specified by the following ABNF:

In addition, the duration MUST NOT include fractional second values unless the fraction is non-zero. A zero duration MUST be represented as P0D.

A PatchObject is of type String[*|null], and represents an unordered set of patches on a JSON object. The keys are a path in a subset of JSON pointer format, with an implicit leading / (i.e. prefix each key with / before applying the JSON pointer evaluation algorithm). The pointer MUST NOT reference inside an array (i.e. you MUST NOT insert/delete from an array; the array MUST be replaced in its entirety instead). Any patch with a key that attempts to do this MUST be ignored. When evaluating a path, all parts prior to the last (i.e. the value after the final slash) MUST exist for the patch to be valid. If not, the patch MUST be ignored. There MUST NOT be two patches in the PatchObject where the pointer of one is the prefix of the pointer of the other, e.g. alerts/1/offset and alerts. The result in this case is undefined. The value associated with each pointer is either: null: Remove the property from the patched object. If not present in the parent, this a no-op. Anything else: The value to replace the inherited property on the patch object with (if present) or add to the property (if not present).

JSCalendar aims at providing unambiguous definitions for value types and properties, but does not define a general normalisation or equivalence method for JSCalendar objects. This is because the notion of equivalence might range from byte-level equivalence to semantic equivalence, depending on the respective use case. For example, the CalDAV protocol requires octet equivalence of the encoded calendar object to determine ETag equivalence. In addition: Custom JSCalendar properties may contain arbitrary JSON values, including arrays. However, equivalence of arrays might or might not depend on the order of elements, depending on the respective property definition. Several JSCalendar property values are defined as URIs and MIME types, but normalisation of these types is inherently protocol and scheme-specific (), depending on the use-case of the equivalence definition. Considering this, the definition of equivalence and normalisation is left to client and server implementations and to be negotiated by a calendar exchange protocol or defined by another RFC.

Vendors MAY add additional properties to the calendar object to support their custom features. The names of these properties MUST be prefixed with a domain name controlled by the vendor to avoid conflict, e.g. fastmail.com/customprop. Some JSCalendar properties allow vendor-specific value extensions. If so, vendor specific values MUST be prefixed with a domain name controlled by the vendor, e.g. fastmail.com/customrel, unless otherwise noted.

JSCalendar objects share a set of common properties, but might only support a subset of them. Refer to the respective object type definitions () for which common properties they support.

Type: String Specifies the type which this object represents. This MUST be one of the following values, registered in a future RFC, or a vendor-specific value: jsevent: a JSCalendar event (). jstask: a JSCalendar task (). jsgroup: a JSCalendar group (). A valid JSCalendar object MUST include this property.

Type: String A globally unique identifier, used to associate the object as the same across different systems, calendars and views. Note that all JSCalendar objects share the same id space, so there MUST NOT be two JSCalendar objects of different type with the same uid. describes a range of established algorithms to generate universally unique identifiers (UUID), and is recommended to use. A valid JSCalendar object MUST include this property.

Type: String[Relation]|null Relates the object to other JSCalendar objects. This is represented as a map of the uid of the related object to information about the relation. A Relation object has the following properties: relation: String[] Describes how the linked object is related to this object. The strings in the array MUST each be at most one of the following values, registered in a future RFC, or a vendor-specific value: first: The linked object is the first in the series this object is part of. next: The linked object is the next in the series this object is part of. child: The linked object is a subpart of this object. parent: This object is part of the overall linked object. If an object is split to make a "this and future" change to a recurrence, the original object MUST be truncated to end at the previous occurrence before this split, and a new object created to represent all the objects after the split. A relation=["next"] relatedTo property MUST be set on the original object with the uid of the new object. A relation=["first"] relatedTo property with the UID of the first object in the series MUST be set on the new object. Clients can then follow these UIDs to get the complete set of objects if the user wishes to modify them all at once.

Type: String|null The identifier for the product that created the JSCalendar object. The vendor of the implementation SHOULD ensure that this is a globally unique identifier, using some technique such as an FPI value, as defined in [ISO.9070.1991]. This property SHOULD NOT be used to alter the interpretation of an JSCalendar object beyond the semantics specified in this document. For example, it is not to be used to further the understanding of non-standard properties.

Type: UTCDate|null The date and time this object was initially created.

Type: UTCDate The date and time the data in this object was last modified.

Type: Number (Defaults to 0 if omitted) Initially zero, this MUST be a non-negative integer that is monotonically incremented each time a change is made to the object.

Type: String|null The iTIP () method, in lower-case. Used for scheduling.

Type: Recurrence Defines a recurrence rule (repeating pattern) for recurring calendar objects. A Recurrence object is a JSON object mapping of a RECUR value type in iCalendar, see and. Objects recur by applying the recurrence rule (and recurrenceOverrides) to the start date/time. A JSTask without a start recurs by its due date/time, if defined. A Recurrence object has the following properties: frequency: String This MUST be one of the following values: yearly monthly weekly daily hourly minutely secondly To convert from iCalendar, simply lower-case the FREQ part. interval: Number(optional, defaults to 1) The INTERVAL part from iCal. If included, it MUST be an integer x >= 1. rscale: String(optional, defaults to "gregorian") The RSCALE part from iCalendar RSCALE, converted to lower-case. skip: String(optional, defaults to "omit") The SKIP part from iCalendar RSCALE, converted to lower-case. firstDayOfWeek: String(optional, defaults to "mo") The WKST part from iCalendar, represented as a lower-case abbreviated two-letter English day of the week. If included, it MUST be one of the following values: "mo"|"tu"|"we"|"th"|"fr"|"sa"|"su". byDay: NDay[](optional) An NDay object has the following properties: day: String The day-of-the-week part of the BYDAY value in iCalendar, lower-cased. MUST be one of the following values: "mo"|"tu"|"we"|"th"|"fr"|"sa"|"su". nthOfPeriod: Number(optional) If present, rather than representing every Friday (for example), it represents only a specific instance within the period (month for monthly recurrences, year for yearly recurrences). Must be a non-zero integer, negative integers means nth-last of period. This is the "+1" or "-3" etc. prefix from the BYDAY values in iCal. byDate: Number[](optional) The BYMONTHDAY part from iCalendar. The array MUST have at least one entry if included. byMonth: String[](optional) The BYMONTH part from iCalendar. 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 Gregorian calendar), with an optional "L" suffix (see ) for leap months (this MUST be upper-case, e.g. "3L"). The array MUST have at least one entry if included. byYearDay: Number[](optional) The BYYEARDAY part from iCalendar. The array MUST have at least one entry if included. byWeekNo: Number[](optional) The BYWEEKNO part from iCalendar. The array MUST have at least one entry if included. byHour: Number[](optional) The BYHOUR part from iCalendar. The array MUST have at least one entry if included. byMinute: Number[](optional) The BYMINUTE part from iCalendar. The array MUST have at least one entry if included. bySecond: Number[](optional) The BYSECOND part from iCalendar. The array MUST have at least one entry if included. count: Number(optional) The COUNT part from iCalendar. This MUST NOT be included if an until property is specified. until: LocalDate(optional) The UNTIL part from iCalendar. This MUST NOT be included if a count property is specified. Note, as in iCalendar, this date is presumed to be in the timezone specified in timeZone. It is not a UTC time.

Type: LocalDate[PatchObject|null]|null The object is a map of the Recurrence-Id (i.e. the date-time of the start of the occurrence) to either null, to indicate the occurrence should be deleted, or an object of patches to apply to the generated occurrence object. If the Recurrence-Id does not match an expanded start date from a recurrence rule, it is to be treated as an additional occurrence (like an RDATE from iCalendar). The patch object may often be empty in this case. By default, an occurrence inherits all properties from the main event except the start (or due) date-time, which is shifted to the new start time. However, individual properties of the occurrence can be modified by a patch, or multiple patches. A pointer in the PatchObject MUST NOT start with one of the following prefixes; any patch with such a key MUST be ignored: uid relatedTo prodId method isAllDay recurrenceRule recurrenceOverrides replyTo

Type: String (Defaults to the empty string if omitted) A short summary of the object.

Type: String (Defaults to the empty string if omitted) A longer form description of the object. This is plain text, but a client SHOULD attempt to hyperlink URLs when displaying it.

Type: String[Location]|null A map of of location id to Location objects, representing locations associated with the object. A location id may be any string and need only be unique to this object, although a UUID is a practical choice. A Location object has the following properties. All properties are optional, but every Location object MUST have at least one property: name: String The human-readable name of the location. description: String Human-readable instructions for accessing this location. This may be an address, set of directions, door access code, etc. rel: String The relation type of this location to the JSCalendar object. This MUST be either one of the following values, registered in a future RFC, or a vendor-specific value. Any value the client or server doesn't understand should be treated the same as unknown. start: The JSCalendar object starts at this location. end: The JSCalendar object ends at this location. virtual: This is not a physical location (e.g. this location is an online chat room where people will meet). unknown: The relation of this location to the event is unknown. features: String[]|null The features supported by this location. The strings in the array MUST each be either one of the following values, registered in a future RFC, or a vendor-specific value. Any value the client or server doesn't understand should be ignored, but preserved. The features supported by locations with rel-type virtual are: audio: audio conferencing chat: chat or instant messaging screen: screen sharing video: video conferencing any vendor-prefixed custom value timeZone: String A time zone for this location. If omitted, the timeZone from the JSCalendar object MUST be presumed when a time zone is needed in relation to this location. coordinates: String An geo: URI for the location. uri: String A URI that represents how to connect to this location. This may be a telephone number (represented as tel:+1-555-555-555) for a teleconference, a web address for online chat, or a custom URI for something like Skype (e.g. skype:username). linkIds: String[]|null A list of ids for links to alternate representations of this location. For example, an alternative representation could be in vCard format. If a given value does not correspond to any link id in the links property of the instance, this MUST be ignored.

Type: String[Link]|null A map of of link id to Link objects, representing external resources associated with the object. A link id may be any string and need only be unique to this object, although the href or a UUID are practical choices. A Link object has the following properties: href: String A URI from which the resource may be fetched. This MAY be a data: URL, but it is recommended that the file be hosted on a server to avoid embedding arbitrary large data in JSCalendar object instances. type: String|null(optional, defaults to null) The content-type of the resource, if known. size: Number|null(optional, defaults to null) The size, in bytes, of the resource when fully decoded (i.e. the number of bytes in the file the user would download), if known. rel: String(optional, defaults to related) Identifies the relation of the linked resource to the object. The value MUST be a registered relation type (see). The features supported by locations with rel-type virtual are: Links with a rel of enclosure SHOULD be considered by the client as attachments for download. Links with a rel of describedby SHOULD be considered by the client to be an alternate representation of the description, for example an HTML page describing the object. Links with a rel of icon SHOULD be considered by the client to be an image that it MAY use when presenting the calendar data to a user. The properties object of this link MAY include a display property indicating the intended purpose of this image. If included, the value MUST be either one of the following values, registered in a future RFC, or a vendor-specific value. badge: an image inline with the title of the object graphic: a full image replacement for the object itself fullsize: an image that is used to enhance the object thumbnail: a smaller variant of fullsize to be used when space for the image is constrained title: String|null(optional, defaults to null) A human-readable description of the resource. properties: String[String|null]|null(optional, defaults to null) Extra metadata stored by a client about a link. The keys are as defined in this document, as defined in a future RFC, or URIs that should be owned by the client author to avoid conflicts.

Type: String|null The language tag that best describes the locale used for the event, if known.

Type: String[PatchObject]|null A map of language tag to a patch object which localises the event into that locale. See the description of PatchObject for the structure of the PatchObject. The patches are applied to the top-level object. In addition to all the restrictions on patches specified there, the pointer also MUST NOT start with one of the following prefixes; any patch with a such a key MUST be ignored: sequence localization start timeZone duration status freeBusyStatus participants useDefaultAlerts

Type: String[]|null A list of keywords or tags related to the object. The values are free-form and do not have to follow any particular structure.

Type: String[]|null Specifies the categories related to the calendar object. Array values MUST be URIs. In contrast to keywords, categories typically are 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 Specifies a color clients MAY use when displaying this event. The value is a case-insensitive color name taken from the CSS3 set of names, defined in Section 4.3 of W3C.REC-css3-color-20110607 or a CSS3 RGB color hex value. It is not intended that clients necessarily use the exact RGB value, but rather that they find a suitable color that works in the given UA context.

Type: Number(defaults to 0 if omitted) Specifies a priority for the event. This may be used as part of scheduling systems to help resolve conflicts for a time period. The priority is specified as an integer in the range 0 to 9. A value of 0 specifies an undefined priority. A value of 1 is the highest priority. A value of 2 is the second highest priority. Subsequent numbers specify a decreasing ordinal priority. A value of 9 is the lowest priority. Other integer values are reserved for future use.

Type: String(defaults to busy if omitted) Specifies how this property should be treated when calculating free-busy state. The value MUST be one of: "free": The object should be ignored when calculating whether the user is busy. "busy": The object should be included when calculating whether the user is busy.

Type: String(defaults to public if omitted) Calendar objects are normally collected together and may be shared with other users. The privacy property allows the object owner to indicate that it should not be shared, or should only have the time information shared but the details withheld. As JSCalendar is simply a data model, enforcement of the restrictions indicated by this property are up to the implementations. This property MUST NOT affect the information sent to scheduled participants; it is only interpreted when the object is shared as part of a shared calendar. The value MUST be either one of the following values, registered in a future RFC, or a vendor-specific value. Vendor specific values MUST be prefixed with a domain name controlled by the vendor, e.g. fastmail.com/topsecret. Any value the client or server doesn't understand should be preserved but treated as equivalent to private. public: The full details of the object are visible to those whom the object's calendar is shared with. private: The details of the object are hidden; only the basic time and metadata is shared. Implementations MUST ensure the following properties are stripped when the object is accessed by a sharee: title description locations links locale localizations participants replyTo In addition, any patches in recurrenceOverrides whose key is prefixed with one of the above properties MUST be stripped. secret: The object is hidden completely (as though it did not exist) when the calendar is shared.

Type: String[String]|null Represents methods by which a participant may RSVP to the organizer of the calendar object. The keys in the property value are the available methods. The value is a URI to use that method. Future methods may be defined in future specifications; a calendar client MUST just ignore any method it does not understand. The following methods are defined: imip: The organizer accepts an iMIP response. The value MUST be a mailto: URI. web: There is a web page where the user may submit an RSVP using their browser. The value MUST be an http: or https: URI.

Type: String[Participant]|null A map of participant id to a participant describing their participation in the calendar object. A participant id may be any string and need only be unique to this event; the email address of the participant is a good choice. A Participant object has the following properties. Properties are mandatory unless marked otherwise: name: String The display name of the participant (e.g. "Joe Bloggs"). email: String The email address for the participant. kind: String(optional, defaults to unknown) What kind of entity this participant is. This MUST be either one of the following values, registered in a future RFC, or a vendor-specific value. Any value the client or server doesn't understand should be treated the same as unknown. individual: a single person group: a collection of people invited as a whole resource: a non-human resource, e.g. a projector location: a physical location involved in the event that needs to be scheduled, e.g. a conference room. unknown: no information is available about the kind of this participant. roles: String[] A list of roles that this participant fulfils. At least one value MUST be specified for the participant. This MUST be either one of the following values, registered in a future RFC, or a vendor-specific value. Any value the client or server doesn't understand should be preserved but ignored. owner: The participant is an organizer of the event, and allowed to make alterations to any part of the event. attendee: The participant is an attendee of the event. chair: The participant is in charge of the event when it occurs. locationId|null: String(optional, defaults to null) The location at which this participant is expected to be attending. If the value does not correspond to any location id in the locations property of the instance, this MUST be treated the same as if the participant's locationId were specified as null. rsvpResponse: String(optional, defaults to needs-action) The RSVP response, if any, of this participant. The value MUST be either one of the following values, registered in a future RFC, or a vendor-specific value: needs-action: No status yet set by the participant. accepted: The participant will attend. declined: The participant may attend. tentative: The participant will not attend. participation: String(optional, defaults to required) The required attendance of this participant. The value MUST be either one of the following values, registered in a future RFC, or a vendor-specific value. Any value the client or server doesn't understand should be treated the same as required. non-participant: Indicates a participant who is copied for information purposes only. optional: Indicates a participant whose participation is optional. required: Indicates a participant whose participation is required. rsvpWanted: Boolean(optional, defaults to false) If true, the organizer is expecting the participant to notify them of their status. scheduleSequence: Number(optional, defaults to 0) The sequence number of the last response from the participant. If defined, this MUST be a non-negative integer. This can be used to determine whether the partcipant has sent a new RSVP following significant changes to the event, and to determine if future responses are responding to a current or older view of the data. scheduleUpdated: UTCDate|null(optional, defaults to null) The updated property of the last iMIP response from the participant. This can be compared to the updated timestamp in future iMIP responses to determine if the response is older or newer than the current data. invitedBy: String|null(optional, defaults to null) The participant id of the participant who invited this one, if known. delegatedTo: String[]|null(optional, defaults to null) A list of participant ids of participants that this participant has delegated their participation to. This MUST be omitted if none (rather than an empty array). delegatedFrom: String[]|null(optional, defaults to null) A list of participant ids that this participant is acting as a delegate for. This MUST be omitted if none (rather than an empty array). memberOf: String[]|null(optional, defaults to null) A list of group addresses that were invited to this calendar object, which caused this participant to be invited due to their membership of the group(s). This MUST be omitted if none (rather than an empty array). linkIds: String[]|null(optional, defaults to null) Links to more information about this participant, for example in vCard format. If a given value does not correspond to any link id in the links property of the instance, this id MUST be ignored. This MUST be omitted if none (rather than an empty array).

Type: Boolean (defaults to false if omitted) If true, use the user's default alerts for this event and ignore the property. Fetching user defaults is dependent on the API from which this JSCalendar object is being fetched, and is not defined in this specification.

Type: String[Alert]|null A map of of alert id to Alert objects, representing alerts/reminders to display or send the user for this calendar object. An alert id may be any string and need only be unique to this calendar object, although a UUID is a practical choice. An Alert Object has the following properties: relativeTo: String (optional, defaults to before-start) Specifies where the offset is relative to for the alarm to trigger. The value MUST be one of: before-start after-start before-end after-end offset: Duration The offset from the start and end/due of the calendar object to fire the alert. If the calendar object does not define a time zone, the user's default time zone SHOULD be used when determining the offset, if known. Otherwise, the time zone to use is implementation specific. action: DisplayAction|EmailAction|UnknownAction Describes how to alert the user. A DisplayAction means a message (which is service dependent, but SHOULD include the title and start or due time of the calendar object) SHOULD be shown to the user on any client connected to this account at the specified time. How this message is formatted (and any sound or other method of drawing the user's attention) is client specific. It has the following properties: type: String The value MUST be display. acknowledged: UTCDate|null (optional) When the user has permanently dismissed the alert the client MUST set this to the current time in UTC. Other clients which sync this property can then automatically dismiss or suppress duplicate alerts (alerts with the same alert id that triggered on or before this date-time). For a recurring event, the acknowledged property of the parent event MUST be updated, unless the alert is already overridden in recurrenceOverrides. snoozed: UTCDate|null (optional) If the user temporarily dismisses the alert, this is the UTC date-time after which it should be reshown. Clients displaying this alert SHOULD hide it if the snoozed property is updated to a time in the future. When that time is reached, the alert SHOULD be reshown unless acknowledged is now after the original trigger time. Setting this property on an instance of a recurring event MUST update the alarm on the master event, unless the respective instance already is defined in recurrenceOverrides. It MUST NOT generate an override for the sole use of snoozing an alarm. audioLinkId: String|null (optional) The id of a link in the property. If the linked file is of an audio type understood by the client, the client SHOULD play this audio when triggering the alert. An EmailAction means an email SHOULD be sent as specified in the object at the specified time. It has the following properties: type: String The value MUST be email. to: Emailer[] An array of name/email objects to send the alert to. An Emailer object has the following properties: name: String The name of the recipient. If not known, clients SHOULD use the empty string. email: String The email address of the recipient. subject: String (optional) The subject to use for the email. If omitted, this is implementation specific, but the server SHOULD try to choose an appropriate subject (such as "Event Summary: starting in 5 min"). textBody: String (optional) The plain-text body to use for the email. If omitted, the body of the email is implementation specific, but the server SHOULD include all pertinent details about the event, such as summary, location and start time. An UnknownAction object is an object that contains a type property whose value is not email or string, plus zero or more other properties. This is for compatibility with client extensions and future RFCs. The client or server SHOULD NOT trigger any type of alert for action types they do not understand, but MUST preserve them.

MIME type: application/calendar+json;type=jsevent A JSEvent represents a scheduled amount of time on a calendar, typically a meeting, appointment, reminder or anniversary. Multiple participants may partake in the event at multiple locations. A JSEvent @type property value MUST be jsevent. In addition to the common JSCalendar object properties a JSEvent has the following properties:

Type: LocalDate e.g. 2015-09-02T00:00:00 The date/time the event would start in the event's time zone. A valid JSEvent MUST include this property.

Type: String|null The IANA Time Zone Database name for the time zone the event is scheduled in, or null for floating time. If omitted, this MUST be presumed to be null (i.e. floating time).

Type: Duration, e.g. P2DT3H (Defaults to P0D if omitted) The zero or positive duration of the event in absolute time (i.e. in UTC time; ignoring DST shifts). To get the end date in the event time zone, convert start into UTC, then add the duration, then convert the result into the appropriate time zone. A JSEvent MAY be end in a different timezone (e.g. a plane flight crossing timezones). In this case, the JSEvent MUST specify the end timezone in a location property value that defines its rel to be end and the end timezone in its timeZone property.

Type: Boolean (optional, defaults to false) Specifies if the event an all day event, such as a birthday or public holiday. If isAllDay is true, then the following restrictions apply: the start property MUST have a time component of T00:00:00. the duration property MUST only include a day component. Note that all-day events MAY be bound to a specific time zone, as defined by the timeZone property.

Type: String The scheduling status () of a JSEvent defaults to confirmed if omitted. If set, it MUST be one of: confirmed: Indicates the event is definite. cancelled: Indicates the event is cancelled. tentative: Indicates the event is tentative.

MIME type: application/calendar+json;type=jstask A JSTask represents an action-item, assignment, to-do or work item . A JSTask @type property value MUST be jstask. A JSTask may start and be due at certain points in time, may take some estimated time to complete and may recur; none of which is required. This notably differs from JSEvent which is required to start at a certain point in time and typically takes some non-zero duration to complete. In addition to the common JSCalendar object properties a JSTask has the following properties:

Type: LocalDate|null e.g. 2015-09-02T00:00:00 The date/time the task is due in the task's time zone.

Type: LocalDate|null e.g. 2015-09-02T00:00:00 The date/time the task should start in the task's time zone.

Type: String|null The IANA Time Zone Database name for the time zone the task is scheduled in, or null for floating time. If omitted, this MUST be presumed to be null (i.e. floating time).

Type: Duration|null, e.g. P2DT3H Specifies the estimated positive duration of time the task takes to complete. If the start and due properties are set, the estimated duration SHOULD be less than or equal to the time interval between these properties.

Type: UTCDate|null, e.g. 2016-06-13T12:00:00Z Specifies the date/time the task was completed. If the task is recurring and has future instances, a client may want to denote a specific task recurrence as completed but leave other instances as uncompleted. One way to achieve this is by overriding the completed property in the task recurrence overrides. However, this could produce a long list of completion times for regularly recurring tasks. An alternative approach is to split the JSTask into a current, single instance of JSTask with this instance completion time and a future recurring instance. Also see the definition of the relatedTo property on splitting.

Type: Boolean (optional, defaults to false) Specifies if the task is an all day task. If isAllDay is true, then the following restrictions apply: the start and due properties MUST have a time component of T00:00:00. the duration and estimatedDuration properties MUST only include a day component. Note that all-day tasks MAY be bound to a specific time zone, as defined by the timeZone property.

In addition to the common properties of a Participant object (), a Participant within a JSTask supports the following property: progress: ParticipantProgress|null The progress of the participant for this task, if known. A ParticipantProgress object has the following properties: status: String Describes the completion status of the participant's progress. The value MUST be at most one of the following values, registered in a future RFC, or a vendor-specific value: completed: The participant completed her part of the task. in-process: The participant is in process of completing her part of the task. timestamp: UTCDate Describes the latest time when the participant updated her progress.

Type: String The scheduling status () of a JSTask defaults to needs-action if omitted. If set, it MUST be one of: needs-action: Indicates the task needs action. completed: Indicates the task is completed. If this value is set, then the timestamp in the completed property () MUST NOT be null. in-process: Indicates the task is in process. cancelled: Indicates the task is cancelled.

MIME type: application/calendar+json;type=jsgroup A JSGroup is a collection of JSEvent and JSTask objects. Typically, objects are grouped by topic (e.g. by keywords) or calendar membership. Its @type property value MUST be jsgroup. JSGroup supports the following JSCalendar properties: @type uid created updated categories keywords name description color links as well as the following JSGroup-specific properties:

Type: (JSTask|JSEvent)[]|null A list of group members. The list MAY contain multiple object types and implementations MUST ignore entries of unknown type. The property value MUST either be null or the list MUST NOT be empty.

Type: String|null (optional, default is null) The source from which updated versions of this group may be retrieved from. If the value is not null, it MUST be a URI.

This section specifies which JSCalendar properties can be mapped from and to iCalendar format. Implementations SHOULD follow these conversion guidelines. Still, JSCalendar does not restrict itself to iCalendar and conversion between these two formats MAY be lossy.

The iCalendar counterpart to JSEvent is the VEVENT component type . A VEVENT component that is a direct child of a VCALENDAR component is equivalent to a standalone JSEvent. A VEVENT component within a VEVENT maps to the entries of the JSEvent recurrenceOverrides property (see ). Property iCalendar counterpart isAllDay True, if the type of the DTSTART property in iCalendar is DATE. When translating from JSCalendar the iCalendar DTSTART property is of DATE value type, if the isAllDay property is set to true and the timeZone property is null. start Corresponds to the DTSTART property in iCalendar. Note that time zone information is stored separately in JSEvent. timeZone Corresponds to the TZID part of the DTSTART property in iCalendar. If the event has a different end time zone to start time zone, this should be added as a JSCalendar location with just a timeZone property and rel="end". duration Corresponds to the DURATION or DSTART+DTEND properties in iCalendar.

The iCalendar counterpart to JSTask is the VTODO component type . A VTODO component that is a direct child of a VCALENDAR component is equivalent to a standalone JSTask. A VTODO component within a master VTODO maps to the entries of the JSTask recurrenceOverrides property (see ). Property iCalendar counterpart isAllDay True, if the type of the DTSTART property in iCalendar is DATE. When translating from JSCalendar the iCalendar DTSTART property is of DATE value type, if the isAllDay property is set to true and the timeZone property is null. due Corresponds to the DUE and DTSTART+DURATION properties in iCalendar. When mapping iCalendar VTODOs with DTSTART+DURATION, the due date is the result of adding DURATION to DTSTART in the DTSTART timezone. start Corresponds to the DTSTART property in iCalendar. timeZone Corresponds to the TZID part of the DTSTART/DUE properties in iCalendar. If the task has a different end time zone to start or due time zone, this should be added as a JSCalendar location with just a timeZone property and rel="end". estimatedDuration Corresponds to the ESTIMATED-DURATION iCalendar property. NON-STANDARD: this property is currently non-standard, see . completed Maps to the COMPLETED iCalendar property. progress Corresponds to the PARTSTAT and COMPLETED properties in iCalendar.

A JSGroup converts to a iCalendar VCALENDAR containing VEVENT or VTODO components. Property iCalendar counterpart entries The VEVENT and VTODO components within a top-level VCALENDAR component. source Corresponds to the SOURCE property in iCalendar.

Property iCalendar counterpart alerts An Alert corresponds to the VALARM component in iCalendar, where the action is determined by the iCalendar ACTION property value (e.g., a DISPLAY property indicates that the JSCalendar Alert action is a DisplayAction and similarly an iCalendar EMAIL value for EmailAction action). The relativeTo and offset properties corresponds to the iCalendar TRIGGER property. NON-STANDARD: The iCalendar properties for JSCalendar Alert actions are non-standard, see . categories Corresponds to the STRUCTURED-CATEGORY property in iCalendar, see. NON-STANDARD: this property is currently non-standard, see . created Corresponds to the CREATED property in iCalendar. description Corresponds to the DESCRIPTION property in iCalendar. freeBusyStatus Corresponds to the TRANSP property in iCalendar. keywords Corresponds to the COLOR property in iCalendar, as specified in . links Corresponds to the ATTACH () and IMAGE iCalendar properties (). locale Corresponds to the LANGUAGE parameter in iCalendar, which is added to individual properties. When converting from iCalendar, one language must be picked as the main locale for the object, and all properties in other languages moved to the localizations JSEvent property. localizations Corresponds to the LANGUAGE parameter in iCalendar, which is added to individual properties. When converting from iCalendar, one language must be picked as the main locale for the object, and all properties in other languages moved to the localizations JSEvent property. locations See . method Corresponds to the METHOD property in iCalendar. participants See . priority Corresponds to the PRIORITY property in iCalendar. privacy Corresponds to the CLASS property in iCalendar. prodId Corresponds to the PRODID property in iCalendar. recurrenceOverrides Corresponds to the RDATE and EXDATE properties in iCalendar, plus VEVENT (for JSEvent) or VTODO (for JSTask) instances with a Recurrence-Id. recurrenceRule Corresponds to the RRULE property in iCalendar. See the property definition at section how to map a RRULE value. relatedTo Corresponds to the RELATED-TO property in iCalendar. replyTo A replyTo property of type imip corresponds to the email address of the ORGANIZER property in iCalendar. There is no iCalendar representation for the web type. sequence Corresponds to the SEQUENCE property in iCalendar. status Corresponds to the STATUS property in iCalendar (converted to lower-case). title Corresponds to the SUMMARY property in iCalendar. uid Corresponds to the UID property in iCalendar. updated Corresponds to the DTSTAMP and LAST-MODIFIED properties in iCalendar. (These are only different in the iTIP case, and the difference is not actually useful.)

Both JSCalendar participants and locations have counterparts in iCalendar but provide richer representation. The following table outlines translation of JSCalendar participants. Where iCalendar has distinct properties for ORGANIZER and ATTENDEE, these are merged in JSCalendar into the Participant object type. Property iCalendar counterpart name the CN parameter kind the CUTYPE parameter rsvpResponse the PARTSTAT parameter role the ORGANIZER and ATTENDEE property name participation the ROLE parameter locationId the JSCalendar identifier of a mapped CONFERENCE property that has the MODERATOR feature defined in its FEATURE parameter values. If multiple such CONFERENCE properties are defined in iCalendar, then the one with the most interactive features is chosen (VIDEO over AUDIO over CHAT over anything else). rsvpWanted the RSVP parameter delegatedTo the DELEGATED-TO parameter delegatedFrom the DELEGATED-FROM parameter memberOf the MEMBER parameter scheduleSequence the SEQUENCE property of the participant's latest iMIP message scheduleUpdated the DTSTAMP property of the participant's latest iMIP message For JSCalendar locations, the iCalendar counterparts are the LOCATION and the extended iCalendar CONFERENCE properties. An iCalendar LOCATION property becomes a JSCalendar Location with just a description property. CONFERENCE property values in iCalendar map to locations with rel type virtual. The location feature property value corresponds to the extended iCalendar FEATURE property parameter values defined in . Both iCalendar PHONE and AUDIO features map to the audio feature and the FEED parameter value is omitted. See the mapping for locationId in on how to map CONFERENCE properties that contain the MODERATOR feature.

Both JSCalendar and iCalendar calendar objects may contain properties that are not expressible in the other format. This specification does not mandate how to preserve these properties. Instead, it leaves negotiation on how to treat unknown properties to client and server implementations and their protocol used to exchange calendar objects. Two notable options to represent and preserve arbitrary iCalendar object properties in JSCalendar are: JCal: Define iCalendar properties in JCal format () in a vendor-specific property of the JCalendar object. The JCal-formatted value may either only contain iCalendar properties that were not mapped to JSCalendar properties, or contain the complete iCalendar object representation. Alternate link: Define an alternate link () value pointing to the iCalendar representation of the JSCalendar object. E.g. the alternative representation of a VEVENT would be represented as a link with rel alternate and type text/calendar;component=VEVENT.

The following examples illustrate several aspects of the JSCalendar data model and format.

This JSEvent object represents a one-time event taking place on September 28 at 4pm, UTC for one hour.

Since properties can be omitted if their default value is used, this can be simplified to:

This JSEvent object represents a recurring event, taking place the first time on January 1, 2016 at 1pm in Vienna, Europe. It recurs monthly, but does not occur on February 1, 2016. In addition to the regular recurrences it also occurs on December 5, 2016 at 5pm, Vienna time. On May 1, it takes place at another location and lasts for two hours, in contrast to the regular one-hour duration.

Note that the recurrenceOverride on May 1 overrides the complete location object. If the event should occur at both locations, the PatchObject would be defined as follows:

The use of JSON as a format does have its own inherent security risks as discussed in Section 12 of . Even though JSON is considered a safe subset of JavaScript, it should be kept in mind that a flaw in the parser processing JSON could still impose a threat, which doesn't arise with conventional iCalendar data. With this in mind, a parser for JSON data aware of the security implications should be used for the format described in this document. For example, the use of JavaScript's eval() function is considered an unacceptable security risk, as described in Section 12 of. A native parser with full awareness of the JSON format should be preferred.

This document amends the application/calendar MIME media type defined in . New optional parameter: type with value being one of jsevent, jstask, jsgroup. The parameter MUST NOT occur more than once.

The author would like to thank the following for their valuable contributions: (TODO:names). This specification originated from the work of the API technical committee of CalConnect, the Calendaring and Scheduling Consortium.