Internet Calendaring and Scheduling Core Object Specification
(iCalendar)
Oracle Corporation600 blvd. de Maisonneuve WestSuite 1900MontrealQCH3A 3J2CANADAbernard.desruisseaux@oracle.comhttp://www.oracle.com/
Applications
This document defines the iCalendar data format for representing
and exchanging calendaring and scheduling information such as
events, to-dos, journal entries and free/busy information,
independent of any particular calendar service or protocol.
This document is a product of the Calendaring and
Scheduling Standards Simplification (Calsify) working
group of the Internet Engineering Task Force. Comments on
this draft are welcomed, and should be addressed to the
ietf-calsify@osafoundation.org mailing list.
The use of calendaring and scheduling has grown considerably
in the last decade. Enterprise and inter-enterprise business
has become dependent on rapid scheduling of events and actions
using this information technology.
This memo
is intended to progress the level of interoperability possible
between dissimilar calendaring and scheduling applications. This
memo defines a MIME content type for exchanging electronic
calendaring and scheduling information. The Internet Calendaring
and Scheduling Core Object Specification, or iCalendar, allows
for the capture and exchange of information normally stored
within a calendaring and scheduling application; such as a
Personal Information Manager (PIM) or a Group Scheduling product.
The iCalendar format is suitable as an exchange format between
applications or systems. The format is defined in terms of a MIME
content type. This will enable the object to be exchanged using
several transports, including but not limited to SMTP, HTTP, a
file system, desktop interactive protocols such as the use of a
memory-based clipboard or drag/drop interactions, point-to-point
asynchronous communication, wired-network transport, or some
form of unwired transport such as infrared might also be used.
The memo also provides for the definition of iCalendar object
methods that will map this content type to a set of messages
for supporting calendaring and scheduling operations such as
requesting, replying to, modifying, and canceling meetings
or appointments, to-dos and journal entries. The iCalendar
object methods can be used to define other calendaring and
scheduling operations such a requesting for and replying with
free/busy time data. Such a scheduling protocol is defined in
the iCalendar Transport-independent Interoperability Protocol
(iTIP) defined in .
The memo also includes a formal grammar for the content type
based on the Internet ABNF defined in
.
This ABNF is required for the implementation of parsers and to serve
as the definitive reference when ambiguities or questions arise in
interpreting the descriptive prose definition of the memo.
Additional restrictions that could not easily be expressed
with the ABNF syntax are specified as comments in the ABNF.
Comments with normative statements should be treated as such.
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 .
This memo makes use of both a descriptive prose and a more formal
notation for defining the calendaring and scheduling format.
The notation used in this memo is the ABNF notation of
.
Readers intending on implementing
the
format defined in this memo should be familiar with this notation
in order to properly interpret the specifications of this memo.
All numeric
values used in this
memo are given in decimal notation.
All names of properties, property parameters, enumerated
property values and property parameter values are
case-insensitive. However, all other property values are
case-sensitive, unless otherwise stated.
Note: All indented editorial notes, such as this one, are intended
to provide the reader with additional information. The information
is not essential to the building of an implementation conformant
with this memo. The information is provided to highlight a
particular feature or characteristic of the memo.
The format for the iCalendar object is based on the syntax of the
text/directory media type .
While the iCalendar object is not a profile of the
text/directory media type ,
it does reuse a number of the elements from the
specification.
The
elements
defined in this memo are defined in prose. Many
of the terms used to describe these have common usage that
is different than the standards usage of this memo. In order
to reference within this memo elements of the calendaring and
scheduling model, core object (this memo) or interoperability
protocol some formatting conventions
have been used. Calendaring and scheduling roles are referred to
in quoted-strings of text with the first character of each word
in upper case. For example, "Organizer" refers to a role of a
"Calendar User" within the scheduling protocol defined by
. Calendar components defined by this memo
are referred to with capitalized, quoted-strings of text. All
calendar components start with the letter "V". For example,
"VEVENT" refers to the event calendar component, "VTODO" refers
to the to-do calendar component and "VJOURNAL" refers to the
daily journal calendar component. Scheduling methods defined
by iTIP are referred to with capitalized,
quoted-strings of text. For example, "REQUEST" refers to
the method for requesting a scheduling calendar component be
created or modified, "REPLY" refers to the method a recipient
of a request uses to update their status with the "Organizer"
of the calendar component.
The properties defined by this memo are referred to with
capitalized, quoted-strings of text, followed by the word
"property". For example, "ATTENDEE" property refers to the
iCalendar property used to convey the calendar address of a
calendar user. Property parameters defined by this memo are
referred to with lowercase, quoted-strings of text, followed by
the word "parameter". For example, "value" parameter refers to
the iCalendar property parameter used to override the default
value type for a property value. Enumerated values defined by
this memo are referred to with capitalized text, either alone
or followed by the word "value". For example, the "MINUTELY"
value can be used with the "FREQ" component of the "RECUR"
value type to specify repeating components based on an interval
of one minute or more.
In this document, descriptions of characters are of the form
"character name (codepoint)", where "codepoint" is from the
US-ASCII character set. The "character name" is the authoritative
description; (codepoint) is a reference to that character
in US-ASCII.
Implementers will need to be familiar with several other
memos that, along with this memo, form a framework for
Internet calendaring and scheduling standards. This memo
specifies a core specification of objects, value types,
properties and property parameters.
iTIP specifies an interoperability
protocol for scheduling between different implementations;
iMIP specifies an Internet email
binding for .
This memo does not attempt to repeat the specification
of concepts or definitions from these other memos. Where
possible, references are made to the memo that provides for
the specification of these concepts or definitions.
The following sections define the details of a Calendaring
and Scheduling Core Object Specification.
The Calendaring and Scheduling Core Object is a collection
of calendaring and scheduling information. Typically, this
information will consist of an iCalendar stream with one or
more iCalendar objects. The body of the iCalendar object
consists of a sequence of calendar properties and one or
more calendar components.
defines the content line format;
defines the property parameter format;
defines the data types for property values;
defines the iCalendar object format;
defines the iCalendar property format;
defines the calendar component format;
defines calendar properties; and
defines calendar component properties.
This information is intended to be an integral part of the MIME
content type registration. In addition, this information can be used
independent of such content registration. In particular, this memo has
direct applicability for use as a calendaring and scheduling exchange
format in file-, memory- or network-based transport mechanisms.
The iCalendar object is organized into individual lines of
text, called content lines. Content lines are delimited by
a line break, which is a CRLF sequence (US-ASCII decimal 13,
followed by US-ASCII decimal 10).
Lines of text SHOULD NOT be longer than 75 octets, excluding
the line break. Long content lines SHOULD be split into
a multiple line representations using a line "folding"
technique. That is, a long line can be split between any
two characters by inserting a CRLF immediately followed by
a single linear white space character (i.e., SPACE, US-ASCII
decimal 32 or HTAB, US-ASCII decimal 9). Any sequence of CRLF
followed immediately by a single linear white space character
is ignored (i.e., removed) when processing the content type.
For example the line:
Can be represented as:
The process of moving from this folded multiple line
representation to its single line representation is called
"unfolding". Unfolding is accomplished by removing the
CRLF character and the linear white space character that
immediately follows.
When parsing a content line, folded lines MUST first be
unfolded according to the unfolding procedure described
above.
Note: It is possible for very simple implementations to
generate improperly folded lines in the middle of a UTF-8
multi-octet sequence. For this reason, implementations
need to unfold lines in such a way to properly restore
the original sequence.
The content information associated with an iCalendar object
is formatted using a syntax similar to that defined by . That is, the content information consists
of CRLF-separated content lines.
The following notation defines the lines of content in an
iCalendar object:
The property value component of a content line has a format
that is property specific. Refer to the section describing
each property for a definition of this format.
All names of properties, property parameters, enumerated
property values and property parameter values are
case-insensitive. However, all other property values are
case-sensitive, unless otherwise stated.
Some properties and parameters allow a list of values. Values
in a list of values MUST be separated by a COMMA character
(US-ASCII decimal 44). There is no significance to the
order of values in a list. For those parameter values (such
as those that specify URI values) that are specified in
quoted-strings, the individual quoted- strings are separated
by a COMMA character (US-ASCII decimal 44).
Some property values are defined in terms of multiple
parts. These structured property values MUST have their
value parts separated by a SEMICOLON character (US-ASCII
decimal 59).
Some properties allow a list of parameters. Each property
parameter in a list of property parameters MUST be separated
by a SEMICOLON character (US-ASCII decimal 59).
Property parameters with values containing a COLON
character (US-ASCII decimal 58),
a SEMICOLON
character (US-ASCII decimal 59)
or a COMMA character
(US-ASCII decimal 44)
MUST be placed in quoted text.
For example, in the following properties a SEMICOLON is
used to separate property parameters from each other, and
a COMMA is used to separate property values in a value list.
Some properties defined in the iCalendar object can have multiple
values. The general rule for encoding multi-valued items is to
simply create a new content line for each value, including the
property name. However, it should be noted that some properties
support encoding multiple values in a single property by separating
the values with a COMMA character (US-ASCII decimal 44). Individual
property definitions should be consulted for determining whether
a specific property allows multiple values and in which of these
two forms.
Multi-valued properties MUST NOT be used to specify multiple
language variants of the same value. Calendar applications
SHOULD display all values.
Binary content information in an iCalendar object SHOULD be
referenced using a URI within a property value. That is the
binary content information SHOULD be placed in an external MIME
entity that can be referenced by a URI from within the iCalendar
object. In applications where this is not feasible, binary
content
information can be included within an iCalendar object, but only
after first encoding it into text using the "BASE64" encoding
method defined in
.
Inline binary
content
SHOULD only be used in applications whose
special circumstances demand that an iCalendar object be expressed
as a single entity. A property containing inline binary content
information MUST specify the "ENCODING" property parameter.
Binary content information placed external to the iCalendar object
MUST be referenced by a uniform resource identifier (URI).
The following example specifies an "ATTACH" property that
references an attachment external to the iCalendar object with
a URI reference:
The following example specifies an "ATTACH" property with inline
binary encoded content information:
There is not a property parameter to declare the
charset
used in a property value. The default
charset
for an iCalendar
stream
is UTF-8 as defined in
.
The "charset" Content-Type parameter
MUST
be used in MIME transports to specify
the charset being used.
A property can have attributes associated with it. These "property
parameters" contain meta-information about the property or the
property value. Property parameters are provided to specify such
information as the location of an alternate text representation
for a property value, the language of a text property value, the
value type of the property value and other attributes.
Property parameter values that contain the COLON (US-ASCII decimal
58), SEMICOLON (US-ASCII decimal 59) or COMMA (US-ASCII decimal 44)
character separators MUST be specified as quoted-string text values.
Property parameter values MUST NOT contain the
DQUOTE
(US-ASCII decimal 22) character. The
DQUOTE
(US-ASCII decimal 22) character is used as a delimiter for
parameter values that contain restricted characters or URI text.
For example:
Property parameter values that are not in quoted strings are case
insensitive.
The general property parameters defined by this memo are defined
by the following notation:
Applications MUST ignore x-param and iana-param value
they don't recognized.
ALTREP
To specify an alternate text representation for the property
value.
This
property parameter is defined by the following notation:
This parameter specifies a URI that points to an
alternate representation for a textual property value. A property
specifying this parameter MUST also include a value that reflects
the default representation of the text value.
The
URI
parameter
value
MUST
be specified in a quoted-string.
Note: While there is no restriction imposed on the
URI schemes allowed for this parameter,
CID,
HTTP, and
HTTPS are
the URI schemes most commonly used by current
implementations.
The "ALTREP" property parameter value might point to a
"text/html" content portion.
CN
To specify the common name to be associated with the
calendar user specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type. The parameter specifies the common name to be
associated with the calendar user specified by the property. The
parameter value is text. The parameter value can be used for
display text to be associated with the calendar address specified
by the property.
CUTYPE
To specify the type of calendar user specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type. The parameter identifies the type of calendar user
specified by the property. If not specified on a property that
allows this parameter, the default is INDIVIDUAL.
Applications MUST treat x-name and iana-token value
they don't recognized the same way as they would
the UNKNOWN value.
DELEGATED-FROM
To specify the calendar users that have delegated their
participation to the calendar user specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type.
This parameter specifies those calendar
users
that have delegated their participation in
a group scheduled event or to-do to the calendar user specified
by the property.
The individual calendar address parameter values MUST each
be specified in a quoted-string.
DELEGATED-TO
To specify the calendar users to whom the calendar user
specified by the property has delegated participation.
This
property parameter is defined by the following
notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type. This parameter specifies those calendar users whom
have been delegated participation in a group scheduled event or
to-do by the calendar user specified by the property.
The individual calendar address parameter values
MUST each be specified in a quoted-string.
DIR
To specify reference to a directory entry associated with
the calendar user specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type. The parameter specifies a reference to the directory
entry associated with the calendar user specified by the
property. The parameter value is a URI. The
URI parameter
value
MUST
be specified in a quoted-string.
Note: While there is no restriction imposed on the
URI schemes allowed for this parameter,
CID,
DATA,
FILE,
FTP,
HTTP,
HTTPS,
LDAP, and
MID are
the URI schemes most commonly used by current
implementations.
ENCODING
To specify an alternate inline encoding for the property value.
This
property parameter is defined by the following notation:
This
property parameter identifies the inline encoding used in a
property value. The default encoding is "8BIT", corresponding
to a property value consisting of text. The "BASE64" encoding
type corresponds to a property value encoded using the "BASE64"
encoding defined in .
If the value type parameter is ";VALUE=BINARY", then the
inline encoding parameter MUST be specified with the value
";ENCODING=BASE64".
FMTTYPE
To specify the content type of a referenced object.
This
property parameter is defined by the following notation:
This parameter can be specified on properties that are used to
reference an object. The parameter specifies the
media type
of the referenced object. For example, on the "ATTACH" property,
a FTP type URI value does not, by itself, necessarily convey
the type of content associated with the resource. The parameter
value MUST be the
text
for either an IANA registered
media
type or a non-standard
media
type.
FBTYPE
To specify the free or busy time type.
This
property parameter is defined by the following notation:
This
parameter specifies the free or busy time type. The value
FREE indicates that the time interval is free for scheduling.
The value BUSY indicates that the time interval is busy because
one or more events have been scheduled for that interval. The
value BUSY-UNAVAILABLE indicates that the time interval is
busy and that the interval can not be scheduled. The value
BUSY-TENTATIVE indicates that the time interval is busy because
one or more events have been tentatively scheduled for that
interval. If not specified on a property that allows this
parameter, the default is BUSY.
Applications MUST treat x-name and iana-token value
they don't recognized the same way as they would
the BUSY value.
The following is an example of this parameter on a
"FREEBUSY"
property.
LANGUAGE
To specify the language for text values in a property or
property parameter.
This
property parameter is defined by the following notation:
This
parameter identifies the language of the text in the property
value and of all
property parameter
values of the property.
The value of the
"LANGUAGE"
property parameter is that defined in
.
For transport in a MIME entity, the Content-Language header
field can be used to set the default language for the entire
body part. Otherwise, no default language is assumed.
The following are examples of this parameter on the
"SUMMARY" and "LOCATION" properties:
MEMBER
To specify the group or list membership of the calendar user
specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a
CAL-ADDRESS value type. The parameter identifies the groups
or list membership for the calendar user specified by the
property. The parameter value
is
either a single calendar address in
a quoted-string or a COMMA character (US-ASCII decimal 44)
separated
list of calendar addresses, each in a quoted-string. The individual
calendar address parameter values MUST each be specified in
a quoted-string.
PARTSTAT
To specify the participation status for the calendar user
specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type. The parameter identifies the participation status for
the calendar user specified by the property value. The parameter
values differ depending on whether they are associated with a
group scheduled "VEVENT", "VTODO" or "VJOURNAL". The values
MUST match one of the values allowed for the given calendar
component.
If not specified on a property that allows this
parameter, the default value is NEEDS-ACTION.
Applications MUST treat x-name and iana-token value
they don't recognized the same way as they would the
NEEDS-ACTION value.
RANGE
To specify the effective range of recurrence instances from
the instance specified by the recurrence identifier specified
by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on a property that specifies
a recurrence identifier. The parameter specifies the
effective range of recurrence instances that is specified
by the property. The effective range is from the recurrence
identifier
specified by the property. If this parameter is not
specified
on
an allowed property, then the default range is the
single instance specified by the recurrence identifier value
of the property.
The parameter value can
only
be "THISANDFUTURE" to indicate a range defined by the
recurrence identifier and all subsequent instances.
The value "THISANDPRIOR" is deprecated by this
revision of iCalendar and MUST NOT be generated by
applications.
RELATED
To specify the relationship of the alarm trigger with
respect to the start or end of the calendar component.
This
property parameter is defined by the following
notation:
This parameter can be specified on properties that specify an
alarm trigger with a "DURATION" value type. The parameter specifies
whether the alarm will trigger relative to the start or end
of the calendar component. The parameter value START will set
the alarm to trigger off the start of the calendar component;
the parameter value END will set the alarm to trigger off the
end of the calendar component. If the parameter is not specified
on an allowable property, then the default is START.
RELTYPE
To specify the type of hierarchical relationship associated
with the calendar component specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on a property that
references another related calendar. The parameter specifies the
hierarchical relationship type of the calendar component referenced
by the property. The parameter value can be PARENT, to indicate that
the referenced calendar component is a superior of calendar
component; CHILD to indicate that the referenced calendar component
is a subordinate of the calendar component; SIBLING to indicate that
the referenced calendar component is a peer of the calendar
component. If this parameter is not specified on an allowable
property, the default relationship type is PARENT.
Applications MUST treat x-name and iana-token value
they don't recognized the same way as they would
the PARENT value.
ROLE
To specify the participation role for the calendar user
specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type. The parameter specifies the participation role
for the calendar user specified by the property in the group
schedule calendar component. If not specified on a property
that allows this parameter, the default value is REQ-PARTICIPANT.
Applications MUST treat x-name and iana-token value
they don't recognized the same way as they would
the REQ-PARTICIPANT value.
RSVP
To specify whether there is an expectation of a favor of a
reply from the calendar user specified by the property value.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type. The parameter identifies the expectation of a reply
from the calendar user specified by the property value. This
parameter is used by the "Organizer" to request a participation
status reply from an "Attendee" of a group scheduled event
or to-do. If not specified on a property that allows this
parameter, the default value is FALSE.
SENT-BY
To specify the calendar user that is acting on behalf of the
calendar user specified by the property.
This
property parameter is defined by the following notation:
This parameter can be specified on properties with a CAL-ADDRESS
value type. The parameter specifies the calendar user that
is acting on behalf of the calendar user specified by the
property. The parameter value MUST be a mailto URI as defined in
.
The individual calendar address
parameter values MUST each be specified in a quoted-string.
TZID
To specify the identifier for the time zone definition for a
time component in the property value.
This property parameter is defined by the following notation:
This parameter MUST be specified on the "DTSTART", "DTEND",
"DUE", "EXDATE" and "RDATE" properties when either a DATE-TIME
or TIME value type is specified and when the value is
not either a UTC or a "floating" time. Refer to the DATE-TIME
or TIME value type definition for a description of UTC and
"floating time" formats. This property parameter specifies a
text value which uniquely identifies the "VTIMEZONE" calendar
component to be used when evaluating the time portion of the
property. The value of the "TZID" property parameter will be equal
to the value of the "TZID" property for the matching time zone
definition. An individual "VTIMEZONE" calendar component MUST
be specified for each unique "TZID" parameter value specified
in the iCalendar object.
The parameter MUST be specified on properties with a DATE-TIME
value if the DATE-TIME is not either a UTC or a "floating" time.
The presence of the SOLIDUS character (US-ASCII decimal 47)
as a prefix, indicates that this "TZID" represents a unique ID
in a globally defined time zone registry (when such registry
is defined).
Note: This document does not define a naming convention for
time zone identifiers. Implementers may want to use the naming
conventions defined in existing time zone specifications such
as the public-domain
TZ database
. The
specification of globally unique time zone identifiers is
not addressed by this document and is left for future study.
The following are examples of this property parameter:
The "TZID" property parameter MUST NOT be applied to
DATE properties, and
DATE-TIME or TIME properties whose time values are specified in UTC.
The use of local time in a DATE-TIME or TIME value without the
"TZID" property parameter is to be interpreted as
floating time,
regardless of the existence of
"VTIMEZONE" calendar components in the iCalendar object.
For more information see the sections on the
value types DATE-TIME and TIME.
VALUE
To explicitly specify the value type format for a property value.
This
property parameter is defined by the following notation:
This
parameter specifies the
value
type and format of the property value. The property values MUST
be of a single value type. For example, a "RDATE" property
cannot have a combination of DATE-TIME and TIME value types.
If the property's value is the default value type, then this
parameter need not be specified. However, if the property's
default value type is overridden by some other allowable value
type, then this parameter MUST be specified.
Applications MUST preserve the value data for x-name
and iana-token values that they don't recognize without
attempting to interpret or parse the value data.
The properties in an iCalendar object are strongly typed. The
definition of each property restricts the value to be one of the
value data types, or simply value types, defined in this section. The
value type for a property will either be specified implicitly as the
default value type or will be explicitly specified with the "VALUE"
parameter. If the value type of a property is one of the alternate
valid types, then it MUST be explicitly specified with the "VALUE"
parameter.
BINARY
This value type is used to identify properties that contain
a character encoding of inline binary data. For example, an
inline attachment of
a document
might be included in an iCalendar object.
This
value type is defined by the following notation:
Property values with this value type MUST also include the inline
encoding parameter sequence of ";ENCODING=BASE64". That is,
all inline binary data MUST first be character encoded using the
"BASE64" encoding method defined in . No
additional content value encoding (i.e., BACKSLASH character
encoding, see )
is defined for this
value type.
The following is an
example of a "BASE64" encoded binary value data.
BOOLEAN
This value type is used to identify properties that contain
either a "TRUE" or "FALSE" Boolean value.
This
value type is defined by the following notation:
These values are case insensitive text. No additional
content value encoding (i.e., BACKSLASH character encoding, see ) is
defined for this value type.
The following is an example of a hypothetical property that
has a BOOLEAN value type:
CAL-ADDRESS
This value type is used to identify properties that contain
a calendar user address.
This
value type is
defined by the following notation:
The value is a URI as defined by
or any other IANA registered form for a URI. When used to address
an Internet email transport address for a calendar user, the value
MUST be a mailto URI, as defined by
.
No additional content value encoding (i.e., BACKSLASH character
encoding, see ) is defined for this value type.
DATE
This value type is used to identify values that contain a
calendar date.
This
value type is defined by the following notation:
If the property permits, multiple "date" values are specified
as a COMMA character (US-ASCII decimal 44) separated list of
values. The format for the value type is
based on
the
complete representation, basic format
for a calendar date. The textual format specifies a four-digit
year, two-digit month, and two-digit day of the month. There
are no separator characters between the year, month and day
component text.
No additional content value encoding (i.e., BACKSLASH character
encoding, see ) is defined for this value type.
The following represents July 14, 1997:
DATE-TIME
This value type is used to identify values that specify a
precise calendar date and time of day.
This
value type is defined by the following notation:
If the property permits, multiple "date-time" values are specified
as a COMMA character (US-ASCII decimal 44) separated list of
values. No additional content value encoding (i.e., BACKSLASH
character encoding, see ) is defined for this value type.
The "DATE-TIME" value type is used to identify values that contain
a precise calendar date and time of day.
The format is based on the
complete representation, basic
format for a calendar date and time of day. The text format is
a concatenation of the "date", followed by the LATIN CAPITAL
LETTER T character (US-ASCII decimal 84) time designator,
followed by the "time" format.
The "DATE-TIME" value type expresses time values in three forms:
The form of date and time with UTC offset MUST NOT be used. For
example, the following is not valid for a date-time value:
FORM #1: DATE WITH LOCAL TIME
The date with local time form is simply a
DATE-TIME
value that does not contain the UTC designator nor does it
reference a time zone. For example, the following represents
January
18, 1998, at 11 PM:
DATE-TIME
values of this type are said to be "floating" and are
not bound to any time zone in particular. They are used to
represent the same hour, minute, and second value regardless
of which time zone is currently being observed. For example,
an event can be defined that indicates that an individual will
be busy from 11:00 AM to 1:00 PM every day, no matter which
time zone the person is in. In these cases, a local time can be
specified. The recipient of an iCalendar object with a property
value consisting of a local time, without any relative time
zone information, SHOULD interpret the value as being fixed to
whatever time zone the "ATTENDEE" is in at any given moment.
This means that two
"Attendees",
in different time zones,
receiving the same event definition as a floating time, may be
participating in the event at different actual times. Floating
time SHOULD only be used where that is the reasonable behavior.
In most cases, a fixed time is desired. To properly communicate
a fixed time in a property value, either UTC time or local time
with time zone reference MUST be specified.
The use of local time in a DATE-TIME value without the "TZID" property
parameter is to be interpreted as floating time, regardless of the
existence of "VTIMEZONE" calendar components in the iCalendar object.
FORM #2: DATE WITH UTC TIME
The date with UTC time, or absolute time, is identified by a
LATIN CAPITAL LETTER Z suffix character (US-ASCII decimal 90),
the UTC designator, appended to the time value. For example,
the following represents January 19, 1998, at 0700 UTC:
The "TZID" property parameter MUST NOT be applied to DATE-TIME
properties whose time values are specified in UTC.
FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE
The date and local time with reference to time zone information
is identified by the use the "TZID" property parameter to reference
the appropriate time zone definition. "TZID" is discussed in
detail in
.
For example, the following represents 2:00 A.M. in New York on
Janurary 19, 1998:
If, based on the definition of the referenced time zone,
the local time described occurs more than once (when changing
from daylight to standard time), the DATE-TIME value refers
to the first occurence of the referenced time. Thus,
TZID=America/New_York:20071104T013000 indicates November
4, 2007 at 1:30 A.M. EDT (UTC-04:00). If the local time
described does not occur (when changing from standard
to daylight time), the DATE-TIME value is interpreted
using the UTC offset before the gap in local times. Thus,
TZID=America/New_York:20070311T023000 indicates March 11,
2007 at 3:30 A.M. EDT (UTC-04:00), one hour after 1:30 A.M.
EST (UTC-05:00).
A time value MUST only specify the second 60 when specifying
a positive leap second. For example:
Implementations which do not support leap seconds SHOULD
interpret the second 60 as equivalent to the second 59.
The following represents July 14, 1997, at 1:30 PM in New York
City in each of the three time formats, using the "DTSTART"
property.
DURATION
This value type is used to identify properties that contain
a duration of time.
This
value type is defined by the following notation:
If the property permits, multiple "duration" values are specified
by a COMMA character (US-ASCII decimal 44) separated list of
values. The format is
based on
the
complete representation
basic format
with designators
for the duration of time.
The format can represent
nominal durations (weeks and days) and accurate
durations (hours, minutes, and seconds).
Note that unlike this
value type doesn't support the "Y" and "M" designators
to specify durations in terms of years and months.
The duration of a week or a day depends on its position in
the calendar. In the case of discontinuities in the time
scale, such as the change from standard time to daylight
time and back, the computation of the exact duration
requires the substraction or addition of the change of
duration of the discontinuity.
Leap seconds MUST NOT be considered when computing an
exact duration.
When computing an exact duration,
the greatest order time components MUST be added first,
that is, the number of days MUST be added first, followed
by the number of hours, number of minutes,
and number of seconds.
Negative durations are typically used to schedule an
alarm to trigger before an associated time
(see ).
No additional content value encoding (i.e., BACKSLASH character
encoding, see ) are defined for this value type.
A duration of 15 days, 5 hours and 20 seconds would be:
A duration of 7 weeks would be:
FLOAT
This value type is used to identify properties that contain
a real number value.
This
value type is defined by the following notation:
If the property permits, multiple "float" values are
specified by a COMMA character (US-ASCII decimal 44) separated list
of values.
No additional content value encoding (i.e., BACKSLASH character
encoding, see ) is defined for this value type.
INTEGER
This value type is used to identify properties that contain
a signed integer value.
This
value type is defined by the following notation:
If the property permits, multiple "integer" values are specified
by a COMMA character (US-ASCII decimal 44) separated list
of values. The valid range for "integer" is -2147483648 to
2147483647. If the sign is not specified, then the value is
assumed to be positive.
No additional content value encoding (i.e., BACKSLASH character
encoding, see ) is defined for this value type.
PERIOD
This value type is used to identify values that contain a
precise period of time.
This value
type is defined by the following notation:
If the property permits, multiple "period" values are specified
by a COMMA character (US-ASCII decimal 44) separated list
of values. There are two forms of a period of time. First,
a period of time is identified by its start and its end. This
format is
based on
the
complete
representation, basic format for "DATE-TIME" start of the period,
followed by a SOLIDUS character (US-ASCII decimal 47), followed
by the "DATE-TIME" of the end of the period. The start of the
period MUST be before the end of the period. Second, a period
of time can also be defined by a start and a positive duration
of time. The format is
based on
the
complete representation, basic format for the "DATE-TIME" start
of the period, followed by a SOLIDUS character (US-ASCII decimal
47), followed by the
basic format for "DURATION" of the period.
The period starting at 18:00:00 UTC, on January 1, 1997 and
ending at 07:00:00 UTC on January 2, 1997 would be:
The period start at 18:00:00 on January 1, 1997 and lasting 5
hours and 30 minutes would be:
No additional content value encoding (i.e., BACKSLASH character
encoding, see ) is defined for this value type.
RECUR
This value type is used to identify properties that contain
a recurrence rule specification.
This
value type is defined by the following notation:
This
value type is a structured value consisting of a
list of one or more recurrence grammar parts. Each rule part is
defined by a NAME=VALUE pair. The rule parts are separated from
each other by the SEMICOLON character (US-ASCII decimal 59).
The rule parts are not ordered in any particular sequence.
Individual rule parts MUST only be specified once.
Compliant applications MUST accept rule parts
ordered in any sequence, but to ensure backward
compatibility with applications that pre-date this
revision of iCalendar the FREQ rule part MUST be the
first rule part specified in a RECUR value.
The FREQ rule part identifies the type of recurrence rule. This
rule part MUST be specified in the recurrence rule.
Valid values include SECONDLY, to specify repeating events based
on an interval of a second or more; MINUTELY, to specify repeating
events based on an interval of a minute or more; HOURLY, to
specify repeating events based on an interval of an hour or
more; DAILY, to specify repeating events based on an interval
of a day or more; WEEKLY, to specify repeating events based on
an interval of a week or more; MONTHLY, to specify repeating
events based on an interval of a month or more; and YEARLY, to
specify repeating events based on an interval of a year or more.
The INTERVAL rule part contains a positive integer representing
at which intervals
the recurrence rule repeats.
The default value is "1", meaning
every second for a SECONDLY rule,
every minute for a MINUTELY rule,
every hour for an HOURLY rule,
every day for a DAILY rule,
every week for a WEEKLY rule,
every month for a MONTHLY
rule,
and every year for a YEARLY rule.
For example, within a DAILY rule,
a value of "8" means every eight days.
The UNTIL rule part defines a
DATE or DATE-TIME
value which bounds the recurrence rule in an inclusive manner.
If the value specified by UNTIL is synchronized with the
specified recurrence, this
DATE or DATE-TIME
becomes the last instance of the recurrence.
The value of the UNTIL rule part MUST have the same value
type as the "DTSTART" property.
Furthermore, if the "DTSTART" property is specified as a
date with local time, then the UNTIL rule part MUST also
be specified as a date with local time. If the
"DTSTART" property is specified as a date with UTC time
or a date with local time and time zone reference, then
the UNTIL rule part MUST be specified as a date with UTC
time.
In the case of the "STANDARD" and "DAYLIGHT" sub-components
the UNTIL rule part MUST always be specified as a date with
UTC time.
If specified as a
DATE-TIME
value, then it MUST be specified in
a
UTC time format. If not present, and the COUNT rule part is
also not present, the "RRULE" is considered to repeat forever.
The COUNT rule part defines the number of occurrences at which
to range-bound the recurrence. The "DTSTART" property
value
always
counts as the first occurrence.
The BYSECOND rule part specifies a COMMA character (US-ASCII
decimal 44) separated list of seconds within a minute. Valid
values are 0 to 60. The BYMINUTE rule part specifies a COMMA
character (US-ASCII decimal 44) separated list of minutes
within an hour. Valid values are 0 to 59. The BYHOUR rule part
specifies a COMMA character (US-ASCII decimal 44) separated
list of hours of the day. Valid values are 0 to 23.
The BYSECOND, BYMINUTE and BYHOUR rule parts MUST NOT be
specified when the associated "DTSTART" property has a DATE
value type. These rule parts MUST be ignored in RECUR value
that violate the above requirement (e.g., generated by
applications that pre-date this revision of iCalendar).
The BYDAY rule part specifies a COMMA character (US-ASCII decimal
44) separated list of days of the week;
SU indicates Sunday;
MO indicates Monday; TU indicates Tuesday;
WE indicates Wednesday; TH indicates Thursday;
FR indicates Friday; SA indicates Saturday.
Each BYDAY value can also be preceded by a positive (+n)
or negative (-n) integer.
If present, this indicates the nth occurrence of
a
specific day within the MONTHLY or YEARLY
"RRULE".
For example, within a MONTHLY rule, +1MO (or simply
1MO) represents the first Monday within the month, whereas
-1MO represents the last Monday of the month.
The numeric value in a BYDAY rule part with the FREQ rule
part set to YEARLY corresponds to an offset within the month
when the BYMONTH rule part is present, and corresponds to
an offset within the year when the BYWEEKNO or BYMONTH rule
parts are present.
If an integer modifier is not present, it means all days of this
type within the specified frequency. For example, within a
MONTHLY rule, MO represents all Mondays within the month.
The BYDAY rule part MUST NOT be specified with a
numeric value when the FREQ rule part is not set
to MONTHLY or YEARLY.
Furthermore, the BYDAY rule part MUST NOT be specified
with a numeric value with the FREQ rule part set to
YEARLY when the BYWEEKNO rule part is specified.
The BYMONTHDAY rule part specifies a COMMA character
(US-ASCII
decimal 44) separated list of days of the month. Valid values
are 1 to 31 or -31 to -1. For example, -10 represents the tenth
to the last day of the month.
The BYMONTHDAY rule part MUST NOT be specified when
the FREQ rule part is set to WEEKLY.
The BYYEARDAY rule part specifies a COMMA character (US-ASCII
decimal 44) separated list of days of the year. Valid values
are 1 to 366 or -366 to -1. For example, -1 represents the last
day of the year (December 31st) and -306 represents the 306th
to the last day of the year (March 1st).
The BYYEARDAY rule part MUST NOT be specified when
the FREQ rule part is set to DAILY, WEEKLY, or
MONTHLY.
The BYWEEKNO rule part specifies a COMMA character (US-ASCII
decimal 44) separated list of ordinals specifying weeks of the
year. Valid values are 1 to 53 or -53 to -1. This corresponds
to weeks according to week numbering as defined in
.
A week is defined as a seven day period,
starting on the day of the week defined to be the week start
(see WKST). Week number one of the calendar year is the first
week which contains at least four (4) days in that calendar
year. This rule part
MUST NOT be used when the FREQ rule part
is set to anything other than YEARLY.
For example, 3 represents the third week of the year.
Note: Assuming a Monday week start, week 53 can only
occur when Thursday is January 1 or if it is a leap year
and Wednesday is January 1.
The BYMONTH rule part specifies a COMMA character (US-ASCII
decimal 44) separated list of months of the year. Valid values
are 1 to 12.
The WKST rule part specifies the day on which the workweek
starts. Valid values are MO, TU, WE, TH, FR, SA and SU. This is
significant when a WEEKLY "RRULE" has an interval greater than 1,
and a BYDAY rule part is specified. This is also significant when
in a YEARLY "RRULE" when a BYWEEKNO rule part is specified. The
default value is MO.
The BYSETPOS rule part specifies a COMMA character
(US-ASCII decimal 44) separated list of values which
corresponds to the nth occurrence within the set of
recurrence instances
specified by the rule.
BYSETPOS operates on a set of recurrence instances in one
interval of the recurrence rule.
For example, in a WEEKLY rule, the interval would be one week
A set of recurrence instances starts at the beginning
of the interval defined by the FREQ rule part.
Valid values are 1 to 366 or -366 to -1. It MUST only be
used in conjunction with another BYxxx rule part. For example
"the last work day of the month" could be represented as:
Each BYSETPOS value can include a positive (+n) or negative
(-n) integer. If present, this indicates the nth occurrence of
the specific occurrence within the set of
occurences
specified by the rule.
Recurrence rules may generate recurrence instances with
invalid date (e.g., February 30) or nonexistent local time
(e.g., 1:30 AM on a day where the local time is moved
forward by an hour at 1:00 AM). Such recurrence instances
MUST be ignored and MUST NOT be counted as part of the
recurrence set.
Information, not contained in the rule, necessary to determine
the various recurrence instance start time and dates are derived
from the Start Time ("DTSTART")
component
attribute. For example,
"FREQ=YEARLY;BYMONTH=1" doesn't specify a specific day within
the month or a time. This information would be the same as what
is specified for "DTSTART".
BYxxx rule parts modify the recurrence in some manner. BYxxx rule
parts for a period of time which is the same or greater than the
frequency generally reduce or limit the number of occurrences of
the recurrence generated. For example, "FREQ=DAILY;BYMONTH=1"
reduces the number of recurrence instances from all days (if
BYMONTH
rule part
is not present) to all days in January. BYxxx
rule parts for a period of time less than the frequency
generally increase or expand the number of occurrences of the
recurrence. For example, "FREQ=YEARLY;BYMONTH=1,2" increases
the number of days within the yearly recurrence set from 1
(if BYMONTH
rule part
is not present) to 2.
If multiple BYxxx rule parts are specified, then after evaluating
the specified FREQ and INTERVAL rule parts, the BYxxx rule
parts are applied to the current set of evaluated occurrences in
the following order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY,
BYDAY, BYHOUR, BYMINUTE, BYSECOND and BYSETPOS; then COUNT and
UNTIL are evaluated.
The table below summarizes the dependency of BYxxx rule part
expand or limit behaviour on the FREQ rule part value.
The term "N/A" means that the corresponding BYxxx rule part
MUST NOT be used with the corresponding FREQ value.
BYDAY has some special behaviour depending on the FREQ value
and this is described in separate notes below the table.
Limit if BYMONTHDAY is present, otherwise special
expand for MONTHLY.
Limit if BYYEARDAY or BYMONTHDAY is present,
otherwise special expand for WEEKLY if BYWEEKNO present,
otherwise special expand for MONTHLY if BYMONTH present,
otherwise special expand for YEARLY.
Here is an example of evaluating multiple BYxxx rule parts.
First, the "INTERVAL=2" would be applied to "FREQ=YEARLY"
to arrive at "every other year". Then, "BYMONTH=1" would be
applied to arrive at "every January, every other year". Then,
"BYDAY=SU" would be applied to arrive at "every Sunday in
January, every other year". Then, "BYHOUR=8,9" would be applied
to arrive at "every Sunday in January at 8 AM and 9 AM, every
other year". Then, "BYMINUTE=30" would be applied to arrive at
"every Sunday in January at 8:30 AM and 9:30 AM, every other
year". Then, lacking information from "RRULE", the second is
derived from "DTSTART", to end up in "every Sunday in January
at 8:30:00 AM and 9:30:00 AM, every other year". Similarly,
if the BYMINUTE, BYHOUR, BYDAY, BYMONTHDAY or BYMONTH rule part
were missing, the appropriate minute, hour, day or month would
have been retrieved from the "DTSTART" property.
If the computed local start time of a recurrence instance
does not exist, or occurs more than once, for the specified
time zone, the time of the recurrence instance is
interpreted in the same manner as an explicit DATE-TIME
value describing that date and time, as specified in
.
No additional content value encoding (i.e., BACKSLASH character
encoding, see ) is defined for this value type.
The following is a rule which specifies 10
occurences
which occur every other day:
There are other examples specified in
.
TEXT
This value type is used to identify values that contain human
readable text.
This
value type is defined by the following notation.
If the property permits, multiple
TEXT
values are specified by
a COMMA character (US-ASCII decimal 44) separated list of values.
The language in which the text is represented can be controlled
by the "LANGUAGE" property parameter.
An intentional formatted text line break MUST only be included
in a "TEXT" property value by representing the line break with
the character sequence of BACKSLASH (US-ASCII decimal 92),
followed by a LATIN SMALL LETTER N (US-ASCII decimal 110)
or a LATIN CAPITAL LETTER N (US-ASCII decimal 78), that is
"\n" or "\N".
The "TEXT" property values may also contain special characters
that are used to signify delimiters, such as a COMMA character
for lists of values or a SEMICOLON character for structured
values. In order to support the inclusion of these special
characters in "TEXT" property values, they MUST be escaped
with a BACKSLASH character. A BACKSLASH character (US-ASCII
decimal 92) in a "TEXT" property value MUST be escaped with
another BACKSLASH character. A COMMA character in a "TEXT"
property value MUST be escaped with a BACKSLASH character
(US-ASCII decimal 92). A SEMICOLON character in a "TEXT"
property value MUST be escaped with a BACKSLASH character
(US-ASCII decimal 92). However, a COLON character in a "TEXT"
property value SHALL NOT be escaped with a BACKSLASH character.
A multiple line value of:
would be represented as:
TIME
This value type is used to identify values that contain a time
of day.
This
value type is defined by the following notation:
If the property permits, multiple "time" values are specified
by a COMMA character (US-ASCII decimal 44) separated list of
values. No additional content value encoding (i.e., BACKSLASH
character encoding, see ) is defined for this value type.
The "TIME"
value
type is used to identify values that contain a time of day.
The format is based on the
complete representation, basic format for a time of day. The
text format consists of a two-digit 24-hour of the day (i.e.,
values 00-23), two-digit minute in the hour (i.e., values 00-59),
and two-digit seconds in the minute (i.e., values 00-60). The
seconds value of 60 MUST only be used to account for
positive
"leap" seconds. Fractions of a second are not supported by
this format.
In parallel to the "DATE-TIME" definition above, the "TIME"
value type expresses time values in three forms:
The form of time with UTC offset MUST NOT be used. For example,
the following is
not valid
for a time value:
FORM #1 LOCAL TIME
The local time form is simply a time value that does not contain
the UTC designator nor does it reference a time zone. For
example, 11:00 PM:
Time values of this type are said to be "floating" and are
not bound to any time zone in particular. They are used to
represent the same hour, minute, and second value regardless
of which time zone is currently being observed. For example,
an event can be defined that indicates that an individual will
be busy from 11:00 AM to 1:00 PM every day, no matter which
time zone the person is in. In these cases, a local time can be
specified. The recipient of an iCalendar object with a property
value consisting of a local time, without any relative time
zone information, SHOULD interpret the value as being fixed to
whatever time zone the "ATTENDEE" is in at any given moment.
This means that two
"Attendees",
may participate in the same event
at different UTC times; floating time SHOULD only be used where
that is reasonable behavior.
In most cases, a fixed time is desired. To properly communicate
a fixed time in a property value, either UTC time or local time
with time zone reference MUST be specified.
The use of local time in a TIME value without the "TZID" property
parameter is to be interpreted as
floating time,
regardless of the existence of "VTIMEZONE" calendar components
in the iCalendar object.
FORM #2: UTC TIME
UTC time, or absolute time, is identified by a LATIN CAPITAL LETTER Z
suffix character (US-ASCII decimal 90), the UTC designator,
appended to the time value. For example, the following represents
07:00 AM UTC:
The "TZID" property parameter MUST NOT be applied to TIME
properties whose time values are specified in UTC.
FORM #3: LOCAL TIME AND TIME ZONE REFERENCE
The local time with reference to time zone information form is
identified by the use the "TZID" property parameter to reference
the appropriate time zone definition. "TZID" is discussed in
detail in
.
The following represents 8:30 AM in New York in Winter, five
hours behind UTC, in each of the three formats:
URI
This value type is used to identify values that contain a
uniform resource identifier (URI) type of reference to the
property value.
This value
type is defined by the following notation:
This value type might be used to reference binary
information, for values that are large, or otherwise undesirable to
include directly in the iCalendar object.
Property values with this value type MUST follow the
generic URI syntax defined in .
When a property parameter value is a URI value type,
the URI MUST be specified as a quoted-string value.
No additional content value encoding (i.e., BACKSLASH
character encoding, see ) is defined for this value type.
The following is a URI for a network file:
UTC-OFFSET
This value type is used to identify properties that contain an
offset from UTC to local time.
This value
type is defined by the following notation:
The PLUS SIGN (US-ASCII decimal 43) character MUST be specified
for positive UTC offsets (i.e., ahead of UTC).
The HYPHEN-MINUS character (US-ASCII decimal 45) MUST be
specified for negative UTC offsets (i.e., behind of UTC).
The value of "-0000" and "-000000" are not allowed.
The time-second, if present,
MUST NOT
be 60; if absent, it defaults to zero.
No additional content value encoding (i.e., BACKSLASH character
encoding, see ) is defined for this value type.
The following UTC offsets are given for standard time for New
York (five hours behind UTC) and Geneva (one hour ahead of UTC):
The Calendaring and Scheduling Core Object is a collection of
calendaring and scheduling information. Typically, this information
will consist of
an iCalendar stream with
a single iCalendar object. However, multiple
iCalendar objects can be sequentially grouped
together
in an iCalendar stream.
The first line and last line of the iCalendar object MUST contain a
pair of iCalendar object delimiter strings. The syntax for an iCalendar
stream
is as follows:
The following is a simple example of an iCalendar object:
A property is the definition of an individual attribute
describing a calendar
object
or a calendar component. A property takes the form defined
by the "contentline" notation defined in
.
The following is an example of a property:
This memo imposes no ordering of properties within an iCalendar
object.
Property names, parameter names and enumerated parameter values are
case insensitive. For example, the property name "DUE" is the same
as "due" and "Due", DTSTART;TZID=America/New_York:19980714T120000 is the
same as DtStart;TzID=America/New_York:19980714T120000.
The body of the iCalendar object consists of a sequence of
calendar properties and one or more calendar components. The
calendar properties are attributes that apply to the calendar
object
as a whole. The calendar components are collections of properties that
express a particular calendar semantic. For example, the calendar
component can specify an event, a to-do, a journal entry, time zone
information,
free/busy time information, or an alarm.
The body of the iCalendar object is defined by the following
notation:
An iCalendar object MUST include the "PRODID" and "VERSION" calendar
properties. In addition, it MUST include at least one calendar
component. Special forms of iCalendar objects are possible to publish
just busy time (i.e., only a "VFREEBUSY" calendar component) or time
zone (i.e., only a "VTIMEZONE" calendar component) information. In
addition, a complex iCalendar object
that is used to capture a complete snapshot of the contents of
a calendar
is possible
(e.g., composite of many different calendar components). More commonly,
an iCalendar object will consist of just a single "VEVENT", "VTODO"
or "VJOURNAL" calendar component.
Applications MUST ignore x-comp and iana-comp they
don't recognized.
Applications that support importing iCalendar objects SHOULD
support all of the component types defined in this document,
and SHOULD NOT silently drop any components as that can lead
to user data loss.
VEVENT
Provide a grouping of component properties that describe
an event.
A "VEVENT" calendar component is defined by the following notation:
A "VEVENT" calendar component is a grouping of component
properties, and possibly including "VALARM" calendar components,
that represents a scheduled amount of time on a calendar. For
example, it can be an activity; such as a one-hour long,
department meeting from 8:00 AM to 9:00 AM, tomorrow. Generally,
an event will take up time on an individual calendar. Hence,
the event will appear as an opaque interval in a search for busy
time. Alternately, the event can have its Time Transparency set
to "TRANSPARENT" in order to prevent blocking of the event in
searches for busy time.
The "VEVENT" is also the calendar component used to specify an
anniversary or daily reminder within a calendar. These events
have a DATE value type for the "DTSTART" property instead of
the default value type of DATE-TIME. If such a "VEVENT" has a
"DTEND" property, it MUST be specified as a DATE value also. The
anniversary type of "VEVENT" can span more than one date
(i.e.,
"DTEND" property value is set to a calendar date after the
"DTSTART" property value).
If such a "VEVENT" has a "DURATION" property, it MUST be
specified as a "dur-day" or "dur-week" value.
The "DTSTART" property for a "VEVENT" specifies the inclusive
start of the event. For recurring events, it also specifies
the very first instance in the recurrence set. The "DTEND"
property for a "VEVENT" calendar component specifies the
non-inclusive end of the event. For cases where a "VEVENT"
calendar component specifies a "DTSTART" property with a DATE
value
type but no "DTEND"
nor "DURATION"
property, the
event's duration is taken to be one day.
For cases where a "VEVENT" calendar component specifies
a "DTSTART" property with a DATE-TIME value type but no "DTEND"
property, the event ends on the same calendar date and time of
day specified by the "DTSTART" property.
The "VEVENT" calendar component cannot be nested within another
calendar component. However, "VEVENT" calendar components can
be related to each other or to a "VTODO" or to a "VJOURNAL"
calendar component with the "RELATED-TO" property.
The following is an example of the "VEVENT" calendar component
used to represent a meeting that will also be opaque to searches
for busy time:
The following is an example of the "VEVENT" calendar component
used to represent a reminder that will not be opaque, but rather
transparent, to searches for busy time:
The following is an example of the "VEVENT" calendar component
used to represent an anniversary that will occur annually.
The following is an example of the "VEVENT" calendar component
used to represent a multi-day event scheduled from June 28th,
2007 to July 8th, 2007 inclusively. Note that the "DTEND"
property is set to July 9th, 2007, since the "DTEND" property
specifies the non-inclusive end of the event.
VTODO
Provide a grouping of calendar properties that describe a to-do.
A "VTODO" calendar component is defined by the following notation:
A "VTODO" calendar component is a grouping of component
properties and possibly "VALARM" calendar components that
represent an action-item or assignment. For example, it can be
used to represent an item of work assigned to an individual;
such as "turn in travel expense today".
The "VTODO" calendar component cannot be nested within another
calendar component. However, "VTODO" calendar components can
be related to each other or to a
"VEVENT"
or to a "VJOURNAL" calendar component with the "RELATED-TO"
property.
A "VTODO" calendar component without the "DTSTART" and "DUE" (or
"DURATION") properties specifies a to-do that will be associated
with each successive calendar date, until it is completed.
The following is an example of a "VTODO" calendar component
that needs to be completed before May 1st, 2007.
On midnight May 1st, 2007 this to-do would be considered
overdue.
The following is an example of a "VTODO" calendar
component
that was due before 1:00 P.M. UTC on July 9th, 2007
and was completed on July 7th, 2007 at 10:00 A.M. UTC.
VJOURNAL
Provide a grouping of component properties that describe a
journal entry.
A "VJOURNAL" calendar component is defined by the following notation:
A "VJOURNAL" calendar component is a grouping of component
properties that represent one or more descriptive text notes
associated with a particular calendar date. The "DTSTART"
property is used to specify the calendar date that the journal
entry is associated with. Generally, it will have a DATE value
data type, but it can also be used to specify a DATE-TIME value
data type. Examples of a journal entry include a daily record
of a legislative body or a journal entry of individual telephone
contacts for the day or an ordered list of accomplishments for
the day. The "VJOURNAL" calendar component can also be used to
associate a document with a calendar date.
The "VJOURNAL" calendar component does not take up time on a
calendar. Hence, it does not play a role in free or busy time
searches
--
it is as though it has a time transparency value
of TRANSPARENT. It is transparent to any such searches.
The "VJOURNAL" calendar component cannot be nested within another
calendar component. However, "VJOURNAL" calendar components
can be related to each other or to a "VEVENT" or to a "VTODO"
calendar component, with the "RELATED-TO" property.
The following is an example of the "VJOURNAL" calendar component:
VFREEBUSY
Provide a grouping of component properties that describe either
a request for free/busy time, describe a response to a request
for free/busy time or describe a published set of busy time.
A "VFREEBUSY" calendar component is defined by the following notation:
A "VFREEBUSY" calendar component is a grouping of component
properties that represents either a request for, a reply to a
request for free or busy time information or a published set
of busy time information.
When used to request free/busy time information, the "ATTENDEE"
property specifies the calendar users whose free/busy time is being
requested; the "ORGANIZER" property specifies the calendar user who
is requesting the free/busy time; the "DTSTART" and "DTEND"
properties specify the window of time for which the free/busy time is
being requested; the "UID" and "DTSTAMP" properties are specified to
assist in proper sequencing of multiple free/busy time requests.
When used to reply to a request for free/busy time, the "ATTENDEE"
property specifies the calendar user responding to the free/busy time
request; the "ORGANIZER" property specifies the calendar user that
originally requested the free/busy time; the "FREEBUSY" property
specifies the free/busy time information (if it exists); and the
"UID" and "DTSTAMP" properties are specified to assist in proper
sequencing of multiple free/busy time replies.
When used to publish busy time, the "ORGANIZER" property specifies
the calendar user associated with the published busy time; the
"DTSTART" and "DTEND" properties specify an inclusive time window
that surrounds the busy time information; the "FREEBUSY" property
specifies the published busy time information; and the "DTSTAMP"
property specifies the date/time that iCalendar object was created.
The "VFREEBUSY" calendar component cannot be nested within another
calendar component. Multiple "VFREEBUSY" calendar components can be
specified within an iCalendar object. This permits the grouping of
Free/Busy information into logical collections, such as monthly
groups of busy time information.
The "VFREEBUSY" calendar component is intended for use in iCalendar
object methods involving requests for free time, requests for busy
time, requests for both free and busy, and the associated replies.
Free/Busy information is represented with the "FREEBUSY" property.
This property provides a terse representation of time periods. One or
more "FREEBUSY" properties can be specified in the "VFREEBUSY"
calendar component.
When present in a "VFREEBUSY" calendar component, the "DTSTART" and
"DTEND" properties SHOULD be specified prior to any "FREEBUSY"
properties.
The recurrence properties ("RRULE",
"RDATE", "EXDATE") are not permitted within a "VFREEBUSY" calendar
component. Any recurring events are resolved into their individual
busy time periods using the "FREEBUSY" property.
The following is an example of a "VFREEBUSY" calendar component
used to request free or busy time information:
The following is an example of a "VFREEBUSY" calendar component
used to reply to the request with busy time information:
The following is an example of a "VFREEBUSY" calendar component
used to publish busy time information.
VTIMEZONE
Provide a grouping of component properties that defines a
time zone.
A "VTIMEZONE" calendar component is defined by the following notation:
A time zone is unambiguously defined by the set of time
measurement rules determined by the governing body for a given
geographic area. These rules describe at a minimum the base offset
from UTC for the time zone, often referred to as the Standard Time
offset. Many locations adjust their Standard Time forward or backward
by one hour, in order to accommodate seasonal changes in number of
daylight hours, often referred to as Daylight Saving Time. Some
locations adjust their time by a fraction of an hour. Standard Time
is also known as Winter Time. Daylight Saving Time is also known as
Advanced Time, Summer Time, or Legal Time in certain countries. The
following table shows the changes in time zone rules in effect for
New York City starting from 1967. Each line represents a description
or rule for a particular observance.
Effective Observance RuleDate(Date/Time)OffsetAbbreviation1967-1973last Sun in Apr, 02:00-0400EDT1967-2006last Sun in Oct, 02:00-0500EST1974-1974Jan 6, 02:00-0400EDT1975-1975Feb 23, 02:00-0400EDT1976-1986last Sun in Apr, 02:00-0400EDT1987-2006first Sun in Apr, 02:00-0400EDT
2007-*
second Sun in Mar, 02:00
-0400
EDT
2007-*
first Sun in Nov, 02:00
-0500
EST
Note: The specification of a global time zone registry is
not addressed by this document and is left for future study.
However, implementers may find the
TZ database
a useful reference.
It is an informal,
public-domain collection of time zone information, which is
currently being maintained by volunteer Internet participants,
and is used in several operating systems. This database contains
current and historical time zone information for a wide variety
of locations around the globe; it provides a time zone identifier
for every unique time zone rule set in actual use since 1970,
with historical data going back to the introduction of standard
time.
Interoperability between two calendaring and scheduling applications,
especially for recurring events, to-dos or journal entries, is
dependent on the ability to capture and convey date and time
information in an unambiguous format. The specification of current
time zone information is integral to this behavior.
If present, the "VTIMEZONE" calendar component defines the set of
Standard Time and Daylight Saving Time observances (or rules) for a
particular time zone for a given interval of time. The "VTIMEZONE"
calendar component cannot be nested within other calendar components.
Multiple "VTIMEZONE" calendar components can exist in an iCalendar
object. In this situation, each "VTIMEZONE" MUST represent a unique
time zone definition. This is necessary for some classes of events,
such as airline flights, that start in one time zone and end in
another.
The "VTIMEZONE" calendar component MUST include the "TZID" property
and at least one definition of a
"STANDARD"
or
"DAYLIGHT"
sub-component.
The
"STANDARD"
or
"DAYLIGHT"
subcomponent
MUST include the "DTSTART", "TZOFFSETFROM" and
"TZOFFSETTO" properties.
An individual "VTIMEZONE" calendar component MUST be specified for
each unique "TZID" parameter value specified in the iCalendar object.
In addition, a "VTIMEZONE" calendar component, referred to
by a recurring calendar component, MUST provide valid time
zone information for all recurrence instances.
Each "VTIMEZONE" calendar component consists of a collection of one
or more sub-components that describe the rule for a particular
observance (either a Standard Time or a Daylight Saving Time
observance). The "STANDARD" sub-component consists of a collection of
properties that describe Standard Time. The "DAYLIGHT" sub-component
consists of a collection of properties that describe Daylight Saving
Time. In general this collection of properties consists of:
the first onset date-time for the observance;
the last onset date-time for the observance, if a last onset
is known;
the offset to be applied for the observance;
a rule that describes the day and time when the observance
takes effect;
an optional name for the observance.
For a given time zone, there may be multiple unique definitions of
the observances over a period of time. Each observance is described
using either a "STANDARD" or "DAYLIGHT" sub-component. The collection
of these sub-components is used to describe the time zone for a given
period of time. The offset to apply at any given time is found by
locating the observance that has the last onset date and time before
the time in question, and using the offset value from that
observance.
The top-level properties in a "VTIMEZONE" calendar component are:
The mandatory "TZID" property is a text value that uniquely
identifies the
"VTIMEZONE"
calendar component within the scope of an iCalendar object.
The optional "LAST-MODIFIED" property is a UTC value that specifies
the date and time that this time zone definition was last updated.
The optional "TZURL" property is a url value
that points to a published "VTIMEZONE" definition. "TZURL" SHOULD
refer to a resource that is accessible by anyone who might
need to interpret the object. This SHOULD NOT normally be a
"file"
URL or other URL that is not widely-accessible.
The collection of properties that are used to define the "STANDARD" and
"DAYLIGHT" sub-components include:
The mandatory "DTSTART" property gives the effective onset date and
local time for the time zone sub-component definition. "DTSTART" in
this usage MUST be specified as a
date with local time
value.
The mandatory "TZOFFSETFROM" property gives the UTC offset which is
in use when the onset of this time zone observance begins.
"TZOFFSETFROM" is combined with "DTSTART" to define the effective
onset for the time zone sub-component definition. For example, the
following represents the time at which the observance of Standard
Time took effect in Fall 1967 for New York City:
The mandatory "TZOFFSETTO" property gives the UTC offset for the
time zone sub-component (Standard Time or Daylight Saving Time) when
this observance is in use.
The optional "TZNAME" property is the customary name for the
time zone.
This could be used for displaying dates.
The
onset
date-times
for the observance defined by the time zone sub-component
is defined by
the
"DTSTART",
"RRULE", and
"RDATE"
properties.
The "RRULE" property defines the recurrence rule for the onset of the
observance defined by this time zone sub-component. Some specific
requirements for the usage of "RRULE" for this purpose include:
If observance is known to have an effective end date, the
"UNTIL" recurrence rule parameter MUST be used to specify the
last valid onset of this observance (i.e., the UNTIL date-time
will be equal to the last instance generated by the recurrence
pattern). It MUST be specified in UTC time.
The "DTSTART" and the
"TZOFFSETFROM"
properties MUST be used when generating the onset date-time
values (instances) from the
"RRULE".
The
"RDATE" property can
also
be used to define the onset of the observance by giving the
individual onset date and times. "RDATE" in this usage MUST
be specified as a
date with local time
value, relative to the UTC offset specified
in the "TZOFFSETFROM" property.
The optional "COMMENT" property is also allowed for descriptive
explanatory text.
The following are examples of the "VTIMEZONE" calendar
component:
This is an example showing all the time zone rules for
New York City since April 30, 1967 at 03:00:00 EDT.
This is an example showing time zone information for
New York City
using
only the "DTSTART"
property. Note that this is only suitable
for a recurring event that starts on or later than
March 11, 2007
at 03:00:00 EDT (i.e., the earliest effective transition
date and time) and ends no later than
March 9, 2008 at 01:59:59 EST
(i.e., latest valid date and time for EST in this scenario).
For example, this can be used for a recurring event that occurs
every Friday,
8:00 A.M.-9:00 A.M.,
starting June 1,
2007,
ending December 31,
2007,
This is a simple example showing the current time zone rules for
New York City
using a "RRULE"
recurrence pattern. Note that there is no effective end date to
either of the Standard Time or Daylight Time rules. This
information would be valid for a recurring event starting
today and continuing indefinitely.
This is an example showing a
set of rules for a fictitious time zone
where the Daylight Time rule has an effective end date
(i.e., after that date, Daylight Time is no longer observed).
This is an example showing a
set of rules for a fictitious time zone
where the first Daylight Time rule has an effective end date.
There is a second Daylight Time rule that picks up where the
other left off.
VALARM
Provide a grouping of component properties that define an alarm.
A "VALARM" calendar component is defined by the following notation:
A "VALARM" calendar component is a grouping of component
properties that is a reminder or alarm for an event or a to-do. For
example, it may be used to define a reminder for a pending event or
an overdue to-do.
The "VALARM" calendar component MUST include the "ACTION" and
"TRIGGER" properties. The "ACTION" property further constrains the
"VALARM" calendar component in the following ways:
When the action is "AUDIO", the alarm can also include one and only
one "ATTACH" property, which MUST point to a sound resource, which is
rendered when the alarm is triggered.
When the action is "DISPLAY", the alarm MUST also include a
"DESCRIPTION" property, which contains the text to be displayed when
the alarm is triggered.
When the action is "EMAIL", the alarm MUST include a "DESCRIPTION"
property, which contains the text to be used as the message body, a
"SUMMARY" property, which contains the text to be used as the message
subject, and one or more "ATTENDEE" properties, which contain the
email address of attendees to receive the message. It can also
include one or more "ATTACH" properties, which are intended to be
sent as message attachments. When the alarm is triggered, the email
message is sent.
The "VALARM" calendar component MUST only appear within either a
"VEVENT" or "VTODO" calendar component. "VALARM" calendar components
cannot be nested. Multiple mutually independent "VALARM" calendar
components can be specified for a single "VEVENT" or "VTODO" calendar
component.
The "TRIGGER" property specifies when the alarm will be triggered.
The "TRIGGER" property specifies a duration prior to the start of an
event or a to-do. The "TRIGGER" edge may be explicitly set to be
relative to the "START" or "END" of the event or to-do with the
"RELATED" parameter of the "TRIGGER" property. The "TRIGGER" property
value type can alternatively be set to an absolute calendar date
with UTC time.
In an alarm set to trigger on the "START" of an event or to-do, the
"DTSTART" property MUST be present in the associated event or to-do.
In an alarm in a "VEVENT" calendar component set to trigger on the
"END" of the event, either the "DTEND" property MUST be present, or
the "DTSTART" and "DURATION" properties MUST both be present. In an
alarm in a "VTODO" calendar component set to trigger on the "END" of
the to-do, either the "DUE" property MUST be present, or the
"DTSTART" and "DURATION" properties MUST both be present.
The alarm can be defined such that it triggers repeatedly. A
definition of an alarm with a repeating trigger MUST include
both the "DURATION" and "REPEAT" properties. The "DURATION"
property specifies the delay period, after which the alarm will
repeat. The "REPEAT" property specifies the number of additional
repetitions that the alarm will be triggered.
This
repetition
count is in addition to the initial triggering of the alarm. Both
of these properties MUST be present in order to specify a
repeating alarm. If one of these two properties is absent,
then the alarm will not repeat beyond the initial trigger.
The "ACTION" property is used within the "VALARM" calendar component
to specify the type of action invoked when the alarm is triggered.
The "VALARM" properties provide enough information for a specific
action to be invoked. It is typically the responsibility of a
"Calendar User Agent" (CUA) to deliver the alarm in the specified
fashion. An "ACTION" property value of AUDIO specifies an alarm that
causes a sound to be played to alert the user; DISPLAY specifies an
alarm that causes a text message to be displayed to the user;
and
EMAIL specifies an alarm that causes an electronic email message
to be delivered to one or more email addresses.
In an AUDIO alarm, if the optional "ATTACH" property is included, it
MUST specify an audio sound resource. The intention is that the sound
will be played as the alarm effect. If an "ATTACH" property is
specified that does not refer to a sound resource, or if the
specified sound resource cannot be rendered (because its format is
unsupported, or because it cannot be retrieved), then the CUA or
other entity responsible for playing the sound may choose a fallback
action, such as playing a built-in default sound, or playing no sound
at all.
In a DISPLAY alarm, the intended alarm effect is for the text value
of the "DESCRIPTION" property to be displayed to the user.
In an EMAIL alarm, the intended alarm effect is for an email message
to be composed and delivered to all the addresses specified by the
"ATTENDEE" properties in the "VALARM" calendar component. The
"DESCRIPTION" property of the "VALARM" calendar component MUST be
used as the body text of the message, and the "SUMMARY" property MUST
be used as the subject text. Any "ATTACH" properties in the "VALARM"
calendar component SHOULD be sent as attachments to the message.
Note: Implementations should carefully consider whether
they accept alarm components from untrusted sources,
e.g., when importing calendar objects from external
sources. One reasonable policy is to always ignore alarm
components that the calendar user has not set herself,
or at least ask for confirmation in such a case.
The following example is for a "VALARM" calendar component that
specifies an audio alarm that will sound at a precise time and
repeat 4 more times at 15 minute intervals:
The following example is for a "VALARM" calendar component that
specifies a display alarm that will trigger 30 minutes before the
scheduled start of the event or
of the to-do it is associated with and will repeat 2 more times
at 15 minute intervals:
The following example is for a "VALARM" calendar component that
specifies an email alarm that will trigger 2 days before the
scheduled due date/time of a to-do it is associated with. It does
not repeat. The email has a subject, body and attachment link.
The Calendar Properties are attributes that apply to the iCalendar
object, as a whole. These properties do not appear within a calendar
component. They SHOULD be specified after the "BEGIN:VCALENDAR"
delimiter string
and prior to any calendar component.
CALSCALE
This property defines the calendar scale used for the calendar
information specified in the iCalendar object.
TEXT
IANA and non-standard
property parameters can be specified on this property.
This property
can be specified
once
in an iCalendar object. The default
value is "GREGORIAN".
This memo is based on the Gregorian calendar scale. The Gregorian
calendar scale is assumed if this property is not specified in
the iCalendar object. It is expected that other calendar scales
will be defined in other specifications or by future versions
of this memo.
This
property is defined by the following notation:
The following is an example of this property:
METHOD
This property defines the iCalendar object method associated
with the calendar object.
TEXT
IANA and non-standard
property parameters can be specified on this property.
This
property can be specified
once
in an iCalendar object.
When used in a MIME message entity, the value of this
property MUST be the same as the Content-Type "method"
parameter value.
If either the "METHOD" property or the
Content-Type "method" parameter is specified, then the other
MUST also be specified.
No methods are defined by this specification. This is the
subject of other specifications, such as the iCalendar
Transport-independent Interoperability Protocol (iTIP)
defined by .
If this property is not present in the iCalendar object,
then a scheduling transaction MUST NOT be assumed. In such
cases, the iCalendar object is merely being used to transport
a snapshot of some calendar information; without the intention
of conveying a scheduling semantic.
This
property is defined by the following notation:
The following is a hypothetical example of this property to
convey that the iCalendar object is a
scheduling
request:
PRODID
This property specifies the identifier for the product that
created the iCalendar object.
TEXT
IANA and non-standard
property parameters can be specified on this property.
The property MUST be specified once in an iCalendar object.
The vendor of the implementation SHOULD assure that this
is a globally unique identifier; using some technique such
as an FPI value, as defined in .
This property SHOULD
NOT
be used to alter the interpretation of an
iCalendar object beyond the semantics specified in this memo. For
example, it is not to be used to further the understanding of
non-standard properties.
This
property is defined by the following notation:
The following is an example of this property. It does not imply
that English is the default language.
VERSION
This property specifies the identifier corresponding to the
highest version number or the minimum and maximum range of the
iCalendar specification that is required in order to interpret
the iCalendar object.
TEXT
IANA and non-standard
property parameters can be specified on this property.
This property MUST be specified
once in
an iCalendar object.
A value of "2.0" corresponds to this memo.
This
property is defined by the following notation:
The following is an example of this property:
The following properties can appear within calendar components,
as specified by each component property definition.
The following properties specify descriptive information about
calendar components.
ATTACH
This
property provides the capability to associate a document
object with a calendar component.
The default value type for this property is URI. The value
type can also be set to BINARY to indicate inline binary
encoded content information.
IANA, non-standard,
inline encoding
and value data type property parameters can be specified
on this property.
The format type parameter can be specified on this property
and is RECOMMENDED for inline binary encoded content
information.
This
property can be specified
multiple times
in a "VEVENT", "VTODO", "VJOURNAL" or "VALARM" calendar
component
with the exception of AUDIO alarm which only allows
this property to occur once
.
This property is used in "VEVENT", "VTODO", and "VJOURNAL"
calendar components to associate a resource (e.g., document)
with the calendar component. This property is used in
"VALARM" calendar components to specify an audio sound
resource or an email message attachment. This property
can be specified as a URI pointing to a resource or as
inline binary encoded content.
When this property is specified as inline binary encoded
content, calendar applications MAY attempt to guess the
media type of the resource via inspection of its content
if and only if the media type of the resource is not
given by the "FMTTYPE" parameter. If the media type
remains unknown, calendar applications SHOULD treat it
as type "application/octet-stream".
This
property is defined by the following notation:
The following are examples of this property:
CATEGORIES
This property defines the categories for a calendar component.
TEXT
IANA, non-standard,
and language property parameters can be specified
on this property.
The property can be specified within "VEVENT", "VTODO" or
"VJOURNAL" calendar components.
This property is used to specify categories or subtypes of the
calendar component. The categories are useful in searching for
a calendar component of a particular type and category. Within
the "VEVENT", "VTODO" or "VJOURNAL" calendar components, more
than one category can be specified as a list of categories
separated by the COMMA character (US-ASCII decimal 44).
This
property is defined by the following notation:
The following are examples of this property:
CLASS
This property defines the access classification for a calendar
component.
TEXT
IANA and non-standard
property parameters can be specified on this property.
The property can be specified once in a "VEVENT", "VTODO" or
"VJOURNAL" calendar components.
An access classification is only one component of the
general security system within a calendar application. It
provides a method of capturing the scope of the access the
calendar owner intends for information within an individual
calendar entry. The access classification of an individual
iCalendar component is useful when measured along with
the other security components of a calendar system (e.g.,
calendar user authentication, authorization, access rights,
access role, etc.). Hence, the semantics of the individual
access classifications cannot be completely defined by
this memo alone. Additionally, due to the "blind" nature
of most exchange processes using this memo, these access
classifications cannot serve as an enforcement statement for
a system receiving an iCalendar object. Rather, they provide
a method for capturing the intention of the calendar owner
for the access to the calendar component.
If not specified in a component that allows this
property, the default value is PUBLIC.
Applications MUST treat x-name and iana-token value
they don't recognized the same way as they would
the PRIVATE value.
This
property is defined by the following notation:
The following is an example of this property:
COMMENT
This property specifies non-processing information intended
to provide a comment to the calendar user.
TEXT
IANA, non-standard,
alternate text representation and language
property parameters can be specified on this property.
This property can be specified
multiple times
in "VEVENT", "VTODO", "VJOURNAL",
and
"VFREEBUSY" calendar components
as well as in the "STANDARD" and "DAYLIGHT"
sub-components.
This property is used to specify a comment to the
calendar user.
This
property is defined by the following notation:
The following is an example of this property:
DESCRIPTION
This property provides a more complete description of the
calendar component, than that provided by the "SUMMARY"
property.
TEXT
IANA, non-standard,
alternate text representation and language
property parameters can be specified on this property.
The property can be specified in the "VEVENT", "VTODO",
"VJOURNAL" or "VALARM" calendar components. The property
can be specified multiple times only within a "VJOURNAL"
calendar component.
This property is used in the "VEVENT" and "VTODO" to capture
lengthy textual decriptions associated with the activity.
This property is used in the "VJOURNAL" calendar component
to capture one
or
more textual journal entries.
This property is used in the "VALARM" calendar component to
capture the display text for a DISPLAY category of alarm,
and
to capture the body text for an EMAIL category of alarm.
This
property is defined by the following notation:
The following is an example of
this
property with formatted
line breaks in the property value:
GEO
This property specifies information related to the global
position for the activity specified by a calendar component.
FLOAT. The value MUST be two SEMICOLON separated FLOAT values.
IANA and non-standard
property parameters can be specified on this property.
This property can be specified in "VEVENT" or "VTODO"
calendar components.
This
property value specifies latitude and longitude, in that
order (i.e., "LAT LON" ordering). The longitude represents the
location
East
or
West
of the prime meridian as a positive or negative real number,
respectively. The longitude and latitude values MAY be
specified up to six decimal places, which will allow for
accuracy to within one meter of geographical position.
Receiving applications MUST accept values of this
precision and MAY truncate values of greater precision.
Values for latitude and longitude shall be expressed as
decimal fractions of degrees. Whole degrees of latitude shall
be represented by a two-digit decimal number ranging from 0
through 90. Whole degrees of longitude shall be represented
by a decimal number ranging from 0 through 180. When a decimal
fraction of a degree is specified, it shall be separated from
the whole number of degrees by a decimal point.
Latitudes North of the equator shall be specified by a plus
sign (+), or by the absence of a minus sign (-), preceding
the digits designating degrees. Latitudes
South of the Equator
shall be designated by a minus sign (-) preceding the digits
designating degrees. A point on the Equator shall be assigned
to the Northern Hemisphere.
Longitudes east of the prime meridian shall be specified
by a plus sign (+), or by the absence of a minus sign (-),
preceding the digits designating degrees. Longitudes west of
the meridian shall be designated by minus sign (-) preceding
the digits designating degrees. A point on the prime meridian
shall be assigned to the Eastern Hemisphere. A point on the
180th meridian shall be assigned to the Western Hemisphere. One
exception to this last convention is permitted. For the special
condition of describing a band of latitude around the earth,
the East Bounding Coordinate data element shall be assigned
the value +180 (180) degrees.
Any spatial address with a latitude of +90 (90) or -90
degrees will specify the position at the North or South
Pole, respectively. The component for longitude may have any
legal value.
With the exception of the special condition described above,
this form is specified in Department of Commerce, 1986,
Representation of geographic point locations for information
interchange (Federal Information Processing Standard 70-1):
Washington, Department of Commerce, National Institute of
Standards and Technology.
The simple formula for converting degrees-minutes-seconds
into decimal degrees is:
decimal = degrees + minutes/60 + seconds/3600.
This
property is defined by the following notation:
The following is an example of this property:
LOCATION
This
property defines the intended venue for the activity
defined by a calendar component.
TEXT
IANA, non-standard,
alternate text representation and language
property parameters can be specified on this property.
This property can be specified in "VEVENT" or "VTODO"
calendar component.
Specific venues such as conference or meeting rooms may
be explicitly specified using this property. An alternate
representation may be specified that is a URI that points to
directory information with more structured specification of
the location. For example, the alternate representation may
specify either an LDAP
URL
pointing to an LDAP server entry
or a CID
URL
pointing to a MIME body part containing a vCard
for the location.
This
property is defined by the following notation:
The following are some examples of this property:
PERCENT-COMPLETE
This property is used by an assignee or delegatee of a to-do
to convey the percent completion of a to-do to the
"Organizer".
INTEGER
IANA and non-standard
property parameters can be specified on this property.
This property can be specified
once
in a "VTODO" calendar component.
The property value is a positive integer between zero and one
hundred. A value of "0" indicates the to-do has not yet been
started. A value of "100" indicates that the to-do has been
completed. Integer values in between indicate the percent
partially complete.
When a to-do is assigned to multiple individuals, the property
value indicates the percent complete for that portion of the
to-do assigned to the assignee or delegatee. For example,
if a to-do is assigned to both individuals "A" and "B". A
reply from "A" with a percent complete of "70" indicates that
"A" has completed 70% of the to-do assigned to them. A reply
from "B" with a percent complete of "50" indicates "B" has
completed 50% of the to-do assigned to them.
This
property is defined by the following notation:
The following is an example of this property to show 39%
completion:
PRIORITY
This
property defines the relative priority for a calendar
component.
INTEGER
IANA and non-standard
property parameters can be specified on this property.
This
property can be specified in
"VEVENT"
and
"VTODO"
calendar components.
This
priority is specified as an integer in the range zero to nine.
A value of zero (US-ASCII decimal 48) specifies an
undefined priority. A value of one (US-ASCII decimal 49) is
the highest priority. A value of two (US-ASCII decimal 50)
is the second highest priority. Subsequent numbers specify
a decreasing ordinal priority. A value of nine (US-ASCII
decimal
57
) is the lowest priority.
A CUA with a three-level priority scheme of "HIGH", "MEDIUM"
and "LOW" is mapped into this property such that a property
value in the range of one (US-ASCII decimal 49) to four
(US-ASCII decimal 52) specifies "HIGH" priority. A value
of five (US-ASCII decimal 53) is the normal or "MEDIUM"
priority. A value in the range of six (US-ASCII decimal 54)
to nine (US-ASCII decimal
57
) is "LOW" priority.
A CUA with a priority schema of "A1", "A2", "A3", "B1",
"B2", ..., "C3" is mapped into this property such that a
property value of one (US-ASCII decimal 49) specifies "A1",
a property value of two (US-ASCII decimal 50) specifies "A2",
a property value of three (US-ASCII decimal 51) specifies "A3",
and so forth up to a property value of 9 (US-ASCII decimal
57
) specifies "C3".
Other integer values are reserved for future use.
Within a "VEVENT" calendar component, this property specifies
a priority for the event. This property may be useful when
more than one event is scheduled for a given time period.
Within a "VTODO" calendar component, this property specified a
priority for the to-do. This property is useful in prioritizing
multiple action items for a given time period.
This
property is
defined
by the following notation:
The following is an example of a property with the highest
priority:
The following is an example of a property with a next highest
priority:
The following is an
example of a property with no priority. This is equivalent
to not specifying the "PRIORITY" property:
RESOURCES
This property defines the equipment or resources anticipated
for an activity specified by a calendar
component.
TEXT
IANA, non-standard,
alternate text representation and language
property parameters can be specified on this property.
This property can be specified
once
in "VEVENT" or "VTODO" calendar component.
The property value is an arbitrary text. More than one
resource can be specified as a list of resources separated
by the COMMA character (US-ASCII decimal 44).
This
property is defined by the following notation:
The following is an example of this property:
STATUS
This property defines the overall status or confirmation for
the calendar component.
TEXT
IANA and non-standard
property parameters can be specified on this property.
This property can be specified
once
in "VEVENT", "VTODO" or "VJOURNAL" calendar components.
In a group scheduled calendar component, the property is used
by the "Organizer" to provide a confirmation of the event to
the "Attendees". For example in a "VEVENT" calendar component,
the "Organizer" can indicate that a meeting is tentative,
confirmed or cancelled. In a "VTODO" calendar component, the
"Organizer" can indicate that an action item needs action,
is completed, is in process or being worked on, or has been
cancelled. In a "VJOURNAL" calendar component, the "Organizer"
can indicate that a journal entry is draft, final or has been
cancelled or removed.
This
property is defined by the following notation:
The following is an example of this property for a "VEVENT"
calendar component:
The following is an example of this property for a "VTODO"
calendar component:
The following is an example of this property for a "VJOURNAL"
calendar component:
SUMMARY
This property defines a short summary or subject for the
calendar component.
TEXT
IANA, non-standard,
alternate text representation and language
property parameters can be specified on this property.
The property can be specified in "VEVENT", "VTODO", "VJOURNAL"
or "VALARM" calendar components.
This property is used in the "VEVENT", "VTODO" and "VJOURNAL"
calendar components to capture a short, one line summary
about the activity or journal entry.
This property is used in the "VALARM" calendar component to
capture the subject of an EMAIL category of alarm.
This
property is defined by the following notation:
The following is an example of this property:
The following properties specify date and time related information
in calendar components.
COMPLETED
This property defines the date and time that a to-do was
actually completed.
DATE-TIME
IANA and non-standard
property parameters can be specified on this property.
The property can be specified in a "VTODO" calendar component.
The value MUST be specified as a date with UTC time.
This property defines the date and time that a to-do was
actually completed.
This
property is defined by the following notation:
The following is an example of this property:
DTEND
This property specifies the date and time that a calendar
component ends.
The default value type is DATE-TIME. The value type can be
set to a DATE value type.
IANA, non-standard,
value data type,
and
time zone identifier property
parameters can be specified on this property.
This property can be specified in "VEVENT" or "VFREEBUSY"
calendar components.
Within the "VEVENT" calendar component, this property defines
the date and time by which the event ends. The
value type of this property MUST be the same as
the "DTSTART" property, and its
value MUST be later in time than the value of the
"DTSTART" property.
Furthermore, this property MUST be specified as a
date with local time if and only if the "DTSTART"
property is also specified as a date with local time.
Within the "VFREEBUSY" calendar component, this property
defines the end date and time for the free or busy time
information. The time MUST be specified in the UTC time
format. The value MUST be later in time than the value of the
"DTSTART" property.
This
property is defined by the following notation:
The following is an example of this property:
DUE
This property defines the date and time that a to-do is
expected to be completed.
The default value type is DATE-TIME. The value type can be
set to a DATE value type.
IANA, non-standard,
value data type,
and
time zone identifier property
parameters can be specified on this property.
The property can be specified once in a "VTODO" calendar
component.
This property defines the date and time before which a
to-do is expected to be completed.
For cases where this property is specified in a "VTODO"
calendar component that also specifies a "DTSTART" property,
the value type of this property MUST be the same as the
"DTSTART" property, and the value of this property MUST be
later in time than the value of the "DTSTART" property.
Furthermore, this property MUST be specified as a
date with local time if and only if the "DTSTART"
property is also specified as a date with local time.
This
property is defined by the following notation:
The following is an example of this property:
DTSTART
This property specifies when the calendar component begins.
The default value type is DATE-TIME. The time value MUST be
one of the forms defined for the DATE-TIME value type. The
value type can be set to a DATE value type.
IANA, non-standard,
value data type,
and
time zone identifier property
parameters can be specified on this property.
This property can be specified
once
in the "VEVENT", "VTODO",
or
"VFREEBUSY"
calendar components
as well as in the "STANDARD" and "DAYLIGHT"
sub-components.
This property is REQUIRED in all types of recurring
calendar components that specify the "RRULE" property.
This property is also REQUIRED in "VEVENT" calendar
components
contained in iCalendar objects that don't specify
the "METHOD" property.
Within the "VEVENT" calendar component, this property
defines the start date and time for the event.
Within the "VFREEBUSY" calendar component, this property
defines the start date and time for the free or busy time
information. The time MUST be specified in UTC time.
Within the
"STANDARD" and "DAYLIGHT" sub-components,
this property defines the effective start date and time for
a time zone specification. This property is REQUIRED within each
"STANDARD"
and "DAYLIGHT"
sub-components
included in "VTIMEZONE" calendar components and MUST be
specified as a
date with local time
without the "TZID" property parameter.
This
property is defined by the following notation:
The following is an example of this property:
DURATION
This
property specifies a positive duration of time.
DURATION
IANA and non-standard
property parameters can be specified on this property.
This
property can be specified in "VEVENT", "VTODO",
or "VALARM" calendar components.
In a "VEVENT" calendar component the property may be used to
specify a duration of the event, instead of an explicit end
date/time. In a "VTODO" calendar component the property may
be used to specify a duration for the to-do, instead of an
explicit due date/time.
In a "VALARM" calendar component the property may be
used to specify the delay period prior to repeating an alarm.
When the "DURATION" property relates to a "DTSTART"
property that is specified as a DATE value, then the
"DURATION" property MUST be specified as a "dur-day"
or "dur-week" value.
This
property is defined by the following notation:
The following is an example of this property that specifies an
interval of time of 1 hour and zero minutes and zero seconds:
The following is an example of this property that specifies
an interval of time of 15 minutes.
FREEBUSY
This
property defines one or more free or busy time intervals.
PERIOD
IANA, non-standard, and
free/busy time type property parameters can
be specified on this property.
The property can be specified in a "VFREEBUSY" calendar
component.
These time periods can be specified as either a start and
end date-time or a start date-time and duration. The date
and time MUST be a UTC time format.
"FREEBUSY" properties within the "VFREEBUSY" calendar component
SHOULD be sorted in ascending order, based on start time and
then end time, with the earliest periods first.
The "FREEBUSY" property can specify more than one value,
separated by the COMMA character (US-ASCII decimal 44). In
such cases, the "FREEBUSY" property values
MUST
all be of
the same "FBTYPE" property parameter type (e.g., all values
of a particular "FBTYPE" listed together in a single property).
This
property is defined by the following notation:
The following are some examples of this property:
TRANSP
This property defines whether an event is transparent or not
to busy time searches.
TEXT
IANA and non-standard
property parameters can be specified on this property.
This property can be specified once in a "VEVENT" calendar
component.
Time Transparency is the characteristic of an event
that determines whether it appears to consume time on a
calendar. Events that consume actual time for the individual
or resource associated with the calendar SHOULD be recorded
as OPAQUE, allowing them to be detected by free-busy time
searches. Other events, which do not take up the individual's
(or resource's) time SHOULD be recorded as TRANSPARENT,
making them invisible to free-busy time searches.
This
property is
defined
by the following notation:
The following is an example of this property for an event that
is transparent or does not block on free/busy time searches:
The following is an example of this property for an event
that is opaque or blocks on free/busy time searches:
The following properties specify time zone information in calendar
components.
TZID
This property specifies the text value that uniquely
identifies the "VTIMEZONE" calendar component
in the scope of an iCalendar object.
TEXT
IANA and non-standard
property parameters can be specified on this property.
This property MUST be specified in a "VTIMEZONE" calendar
component.
This is the label by which a time zone calendar component is
referenced by any iCalendar properties whose value type is
either DATE-TIME or TIME and not intended to specify a UTC
or a "floating" time. The presence of the SOLIDUS character
(US-ASCII decimal 47) as a prefix, indicates that this "TZID"
represents an unique ID in a globally defined time zone
registry (when such registry is defined).
Note: This document does not define a naming convention for
time zone identifiers. Implementers may want to use the naming
conventions defined in existing time zone specifications such
as the public-domain
TZ database
. The
specification of globally unique time zone identifiers is not
addressed by this document and is left for future study.
This property is defined by the following notation:
The following are examples of non-globally unique time zone
identifiers:
The following is an example of a fictitious globally unique
time zone identifier:
TZNAME
This property specifies the customary designation for a time
zone description.
TEXT
IANA, non-standard,
and language property parameters can be specified
on this property.
This property can be specified in
"STANDARD" and "DAYLIGHT" sub-components.
This property
specifies a customary name that can be used when
displaying dates that occur during the observance
defined by the time zone sub-component.
This property is defined by the following notation:
The following are examples of this property:
TZOFFSETFROM
This property specifies the offset which is in use prior to
this time zone observance.
UTC-OFFSET
IANA and non-standard
property parameters can be specified on this property.
This property MUST be specified in
"STANDARD" and "DAYLIGHT" sub-components.
This property specifies the offset which is in use prior to
this time observance. It is used to calculate the absolute
time at which the transition to a given observance takes
place. This property MUST only be specified in a "VTIMEZONE"
calendar component. A "VTIMEZONE" calendar component MUST
include this property. The property value is a signed numeric
indicating the number of hours and possibly minutes from
UTC. Positive numbers represent time zones east of the prime
meridian, or ahead of UTC. Negative numbers represent time
zones west of the prime meridian, or behind UTC.
This
property is defined by the following notation:
The following are examples of this property:
TZOFFSETTO
This property specifies the offset which is in use in this
time zone observance.
UTC-OFFSET
IANA and non-standard
property parameters can be specified on this property.
This property MUST be specified in
"STANDARD" and "DAYLIGHT" sub-components.
This property specifies the offset which is in use in this
time zone observance. It is used to calculate the absolute
time for the new observance. The property value is a signed
numeric indicating the number of hours and possibly minutes
from UTC. Positive numbers represent time zones east of the
prime meridian, or ahead of UTC. Negative numbers represent
time zones west of the prime meridian, or behind UTC.
This
property is defined by the following notation:
The following are examples of this property:
TZURL
This property
provides a means for a
"VTIMEZONE"
component to point to a network location that can be used to
retrieve an up-to-date version of itself.
URI
IANA and non-standard
property parameters can be specified on this property.
This property can be specified in a "VTIMEZONE" calendar
component.
This property
provides a means for a "VTIMEZONE" component to point
to a network location that can be used to retrieve an up-to-date
version of itself. This provides a hook to handle changes
government bodies impose upon time zone definitions. Retrieval
of this resource results in an iCalendar object containing
a single "VTIMEZONE" component and a "METHOD" property set
to PUBLISH.
This
property is defined by the following notation:
The following is an example of this property:
The following properties specify relationship information in
calendar components.
ATTENDEE
This
property defines an "Attendee" within a calendar component.
CAL-ADDRESS
IANA, non-standard,
language, calendar user type, group or list
membership, participation role, participation status, RSVP
expectation, delegatee, delegator, sent by, common name or
directory entry reference property parameters can be specified
on this property.
This property MUST be specified in an iCalendar object that
specifies a group scheduled calendar entity. This property
MUST NOT be specified in an iCalendar object when publishing
the calendar information (e.g., NOT in an iCalendar object
that specifies the publication of a calendar user's busy time,
event, to-do or journal). This property is not specified in
an iCalendar object that specifies only a time zone definition
or that defines calendar
components
that are not group scheduled
components,
but are
components
only on a single user's calendar.
This
property MUST only be specified within calendar components
to specify participants, non-participants and the chair of
a group scheduled calendar entity. The property is specified
within an "EMAIL" category of the "VALARM" calendar component
to specify an email address that is to receive the email type
of iCalendar alarm.
The property parameter "CN" is for the common or displayable name
associated with the calendar address; "ROLE", for the intended
role that the attendee will have in the calendar component;
"PARTSTAT", for the status of the attendee's participation;
"RSVP", for indicating whether the favor of a reply is
requested; "CUTYPE", to indicate the type of calendar user;
"MEMBER", to indicate the groups that the attendee belongs to;
"DELEGATED-TO", to indicate the calendar users that the original
request was delegated to; and "DELEGATED-FROM", to indicate whom
the request was delegated from; "SENT-BY", to indicate whom is
acting on behalf of the "ATTENDEE"; and "DIR", to indicate the
URI that points to the directory information corresponding
to the attendee. These property parameters can be specified
on an "ATTENDEE" property in either a "VEVENT", "VTODO" or
"VJOURNAL" calendar component. They MUST
NOT
be specified in an "ATTENDEE" property in a
"VFREEBUSY" or "VALARM" calendar component. If the
"LANGUAGE"
property parameter is specified, the identified language
applies to the "CN" parameter.
A recipient delegated a request MUST inherit the "RSVP" and "ROLE"
values from the attendee that delegated the request to them.
Multiple attendees can be specified by including multiple
"ATTENDEE" properties within the calendar component.
This
property is defined by the following notation:
The following are examples of this property's use for a to-do:
The following is an example of this property used for
specifying multiple attendees to an event:
The following is an example of this property with a URI to
the directory information associated with the attendee:
The following is an example of this property with "delegatee"
and "delegator" information for an event:
The following is an example of this property's use when
another calendar user is acting on behalf of the "Attendee":
CONTACT
This
property is used to represent contact information or
alternately a reference to contact information associated
with the calendar component.
TEXT
IANA, non-standard,
alternate text representation and language
property parameters can be specified on this property.
This
property can be specified in a "VEVENT", "VTODO", "VJOURNAL"
or "VFREEBUSY" calendar component.
The property value consists of textual contact information. An
alternative representation for the property value can also be
specified that refers to a URI pointing to an alternate form,
such as a vCard , for the contact
information.
This
property is defined by the following notation:
The following is an example of this property referencing
textual contact information:
The following is an example of this property with an alternate
representation of a LDAP URI to a directory entry containing
the contact information:
The following is an example of this property with an alternate
representation of a MIME body part containing the contact
information, such as a vCard embedded
in a
text/directory media type :
The following is an example of this property referencing a
network resource, such as a vCard
object containing the contact information:
ORGANIZER
This
property defines the organizer for a calendar component.
CAL-ADDRESS
IANA, non-standard,
language, common name, directory entry reference,
sent by property parameters can be specified on this property.
This property MUST be specified in an iCalendar object that
specifies a group scheduled calendar entity. This property
MUST be specified in an iCalendar object that specifies the
publication of a calendar user's busy time. This property
MUST NOT be specified in an iCalendar object that specifies
only a time zone definition or that defines calendar
components
that are not group scheduled
components,
but are
components
only on a single user's calendar.
This
property is specified within the "VEVENT", "VTODO",
"VJOURNAL" calendar components to specify the organizer of a
group scheduled calendar entity. The property is specified
within the "VFREEBUSY" calendar component to specify the
calendar user requesting the free or busy time. When publishing
a "VFREEBUSY" calendar component, the property is used to
specify the calendar that the published busy time came from.
The property has the property parameters "CN", for specifying
the common or display name associated with the "Organizer",
"DIR", for specifying a pointer to the directory information
associated with the "Organizer", "SENT-BY", for specifying
another calendar user that is acting on behalf of
the "Organizer". The non-standard parameters may also
be specified on this property. If the "LANGUAGE" property
parameter is specified, the identified language applies to
the "CN" parameter value.
This
property is defined by the following notation:
The following is an example of this property:
The following is an example of this property with a pointer
to the directory information associated with the organizer:
The following is an example of this property used by another
calendar user who is acting on behalf of the organizer,
with responses intended to be sent back to the organizer,
not the other calendar user:
RECURRENCE-ID
This property is used in conjunction with the "UID"
and "SEQUENCE" property to identify a specific instance
of a recurring "VEVENT", "VTODO" or "VJOURNAL" calendar
component. The property value is the
original
value of the "DTSTART" property of the recurrence instance.
The default value type for this property is DATE-TIME.
The default value type is DATE-TIME.
The value type can be set to a DATE value type.
This property MUST have the same value type as the
"DTSTART" property contained within the recurring
component. Furthermore, this property MUST be specified
as a date with local time if and only if the "DTSTART"
property contained within the recurring component is
specified as a date with local time.
IANA, non-standard,
value data type, time zone identifier and recurrence identifier
range parameters can be specified on this property.
This property can be specified in an iCalendar object
containing a recurring calendar component.
The full range of calendar components specified by a recurrence
set is referenced by referring to just the "UID" property value
corresponding to the calendar component. The "RECURRENCE-ID"
property allows the reference to an individual instance within
the recurrence set.
If the value of the "DTSTART" property is a DATE type value,
then the value MUST be the calendar date for the recurrence
instance.
The
DATE-TIME
value is set to the time when the original
recurrence instance would occur; meaning that if the intent
is to change a Friday meeting to Thursday, the
DATE-TIME
is still set to the original Friday meeting.
The "RECURRENCE-ID" property is used in conjunction with the
"UID" and "SEQUENCE" property to identify a particular instance
of a recurring event, to-do or journal. For a given pair of
"UID" and "SEQUENCE" property values, the "RECURRENCE-ID" value
for a recurrence instance is fixed.
The "RANGE" parameter is used to specify the effective range
of recurrence instances from the instance specified by the
"RECURRENCE-ID" property value. The
value for the range parameter
can only be
"THISANDFUTURE" to indicate a range defined by the
given recurrence instance and all subsequent instances.
Subsequent instances are determined by their "RECURRENCE-ID"
value and not their current scheduled start time.
Subsequent instances defined in separate components
are not impacted by the given recurrence instance.
When the given recurrence instance is rescheduled,
all subsequent instances are also rescheduled by
the same time difference. For instance, if the
given recurrence instance is rescheduled to start
2 hours later, then all subsequent instances are
also rescheduled 2 hours later. Similarly, if the
duration of the given recurrence instance is
modified, then all subsequence instances are also
modified to have this same duration.
Note: The "RANGE" parameter may not be appropriate
to reschedule specific subsequent instances of
complex recurring calendar component.
Assuming an unbounded recurring calendar component
scheduled to occur on Mondays and Wednesdays, the
"RANGE" parameter could not be used to reschedule
only the future Monday instances to occur on Tuesday
instead. In such cases, the calendar application could
simply truncate the unbounded recurring calendar
component (i.e., with the "COUNT" or "UNTIL" rule
parts), and create two new unbounded recurring calendar
components for the future instances.
This
property is defined by the following notation:
The following are examples of this property:
RELATED-TO
This
property is used to represent a relationship or reference
between one calendar component and another.
TEXT
IANA, non-standard,
and relationship type property parameters can
be specified on this property.
This
property can be specified
in the "VEVENT", "VTODO"
and
"VJOURNAL" calendar components.
The property value consists of the persistent, globally unique
identifier of another calendar component. This value would
be represented in a calendar component by the "UID" property.
By default, the property value points to another calendar
component that has a PARENT relationship to the referencing
object. The "RELTYPE" property parameter is used to either
explicitly state the default PARENT relationship type to the
referenced calendar component or to override the default
PARENT relationship type and specify either a CHILD or
SIBLING relationship. The PARENT relationship indicates that
the calendar component is a subordinate of the referenced
calendar component. The CHILD relationship indicates that the
calendar component is a superior of the referenced calendar
component. The SIBLING relationship indicates that the calendar
component is a peer of the referenced calendar component.
Changes to a calendar component referenced by this property can
have an implicit impact on the related calendar component. For
example, if a group event changes its start or end date
or time, then the related, dependent events will need to
have their start and end dates changed in a corresponding
way. Similarly, if a PARENT calendar component is
cancelled
or deleted, then there is an implied impact to the related CHILD
calendar components. This property is intended only to provide
information on the relationship of calendar components. It
is up to the target calendar system to maintain any property
implications of this relationship.
This
property is defined by the following notation:
The following is an example of this property:
URL
This property defines a Uniform Resource Locator (URL)
associated with the iCalendar object.
URI
IANA and non-standard
property parameters can be specified on this property.
This property can be specified once in the "VEVENT", "VTODO",
"VJOURNAL" or "VFREEBUSY" calendar components.
This property may be used in a calendar component to convey
a location where a more dynamic rendition of the calendar
information associated with the calendar component can be
found. This memo does not attempt to standardize the form
of the URI, nor the format of the resource pointed to by
the property value. If the URL property and Content-Location
MIME header are both specified, they MUST point to the same
resource.
This
property is defined by the following notation:
The following is an example of this property:
UID
This property defines the persistent, globally unique
identifier for the calendar component.
TEXT
IANA and non-standard
property parameters can be specified on this property.
The property MUST be specified in the "VEVENT", "VTODO",
"VJOURNAL" or "VFREEBUSY" calendar components.
The "UID"
itself MUST be a globally unique identifier. The
generator of the identifier MUST guarantee that the identifier
is unique. There are several algorithms that can be used
to accomplish this.
A good method to assure uniqueness is to put the
domain name or a domain literal IP address of the host on
which the identifier was created on the right hand side of
an
"@", and on the left hand side, put a combination
of the current calendar date
and time of day (i.e., formatted in as a DATE-TIME value)
along with some other currently unique (perhaps sequential)
identifier available on the system (for example, a process
id number). Using a date/time value on the left hand side
and a domain name or domain literal on the right hand side
makes it possible to guarantee uniqueness since no two hosts
should be using the same domain name or IP address at the same
time. Though other algorithms will work, it is RECOMMENDED that
the right hand side contain some domain identifier (either
of the host itself or otherwise) such that the generator of
the message identifier can guarantee the uniqueness of the
left hand side within the scope of that domain.
This is the method for correlating scheduling messages with the
referenced "VEVENT", "VTODO", or "VJOURNAL" calendar component.
The full range of calendar components specified by a recurrence
set is referenced by referring to just the "UID" property value
corresponding to the calendar component. The "RECURRENCE-ID"
property allows the reference to an individual instance within
the recurrence set.
This property is an important method for group scheduling
applications to match requests with later replies,
modifications or deletion requests. Calendaring and scheduling
applications MUST generate this property in "VEVENT", "VTODO"
and "VJOURNAL" calendar components to assure interoperability
with other group scheduling applications. This identifier is
created by the calendar system that generates an iCalendar
object.
Implementations MUST be able to receive and persist values
of at least 255
octets
for this property
but MUST NOT truncate values in the middle of a UTF-8 multi-octet sequence.
This
property is defined by the following notation:
The following is an example of this property:
The following properties specify recurrence information in calendar
components.
EXDATE
This property defines the list of date/time exceptions for
recurring events, to-dos, journal entries
or time zone definitions.
The default value type for this property is DATE-TIME.
The value type can be set to DATE.
IANA, non-standard,
value data type and time zone identifier property
parameters can be specified on this property.
This property can be specified in
recurring "VEVENT", "VTODO", and "VJOURNAL" calendar
components as well as in the "STANDARD" and "DAYLIGHT"
sub-components of the "VTIMEZONE" calendar component.
The exception dates, if specified, are used in computing the
recurrence set. The recurrence set is the complete set of
recurrence instances for a calendar component. The recurrence
set is generated by considering the initial "DTSTART"
property along with the "RRULE", "RDATE",
and
"EXDATE"
properties contained within the
recurring component.
The "DTSTART" property defines the first instance in the
recurrence set.
The "DTSTART" property value SHOULD match the pattern of
the recurrence rule, if specified. The recurrence set
generated with a "DTSTART" property value that doesn't
match the pattern of the rule is undefined.
The final recurrence set is generated by gathering all
of the start date-times generated by any of the specified
"RRULE" and "RDATE" properties, and then excluding any start
date and times
specified by "EXDATE" properties.
This implies that start date and times
specified by "EXDATE" properties
take precedence over those specified by inclusion properties
(i.e., "RDATE" and "RRULE").
When
duplicate instances are generated by the "RRULE" and "RDATE"
properties, only one recurrence is considered. Duplicate
instances are ignored.
The "EXDATE" property can be used to exclude the value
specified in "DTSTART". However, in such cases the original
"DTSTART" date MUST still be maintained by the calendaring and
scheduling system because the original "DTSTART" value has
inherent usage dependencies by other properties such as the
"RECURRENCE-ID".
This
property is defined by the following notation:
The following is an example of this property:
RDATE
This property defines the list of date/times for
recurring events, to-dos, journal entries
or time zone definitions.
The default value type for this property is DATE-TIME.
The value type can be set to DATE or PERIOD.
IANA, non-standard,
value data type and time zone identifier property
parameters can be specified on this property.
This
property can be specified in
recurring
"VEVENT", "VTODO",
and
"VJOURNAL"
calendar components
as well as in the "STANDARD" and "DAYLIGHT" sub-components
of the "VTIMEZONE" calendar component.
This property can appear along with the "RRULE" property to
define an aggregate set of repeating occurrences. When they
both appear in
a recurring component,
the
recurrence instances
are defined by the union of occurrences defined by
both the "RDATE" and "RRULE".
The recurrence dates, if specified, are used in computing
the recurrence set. The recurrence set is the complete
set of recurrence instances for a calendar component. The
recurrence set is generated by considering the initial
"DTSTART" property along with the "RRULE", "RDATE",
and
"EXDATE"
properties contained within the
recurring component.
The "DTSTART" property defines the first instance in
the recurrence set.
The "DTSTART" property value SHOULD match the pattern of
the recurrence rule, if specified. The recurrence set
generated with a "DTSTART" property value that doesn't
match the pattern of the rule is undefined.
The final recurrence set is generated by gathering all
of the start date-times generated by any of the specified
"RRULE" and "RDATE" properties, and then excluding any start
date and times
specified by "EXDATE" properties.
This implies that start date/times
specified by "EXDATE" properties
take precedence over those specified by inclusion properties
(i.e., "RDATE" and "RRULE"). Where duplicate instances are
generated by the "RRULE" and "RDATE" properties, only one
recurrence is considered. Duplicate instances are ignored.
This
property is defined by the following notation:
The following are examples of this property:
RRULE
This property defines a rule or repeating pattern for
recurring events, to-dos,
journal entries
or time zone definitions.
RECUR
IANA and non-standard
property parameters can be specified on this
property.
This property can be specified
in recurring "VEVENT", "VTODO" and "VJOURNAL" calendar
components
as well as in the "STANDARD" and "DAYLIGHT" sub-components
of the "VTIMEZONE" calendar component, but it SHOULD NOT
be specified more than once. The recurrence set generated
with multiple "RRULE" properties is undefined.
The recurrence rule, if specified, is used in computing
the recurrence set. The recurrence set is the complete
set of recurrence instances for a calendar component. The
recurrence set is generated by considering the initial
"DTSTART" property along with the "RRULE", "RDATE",
and
"EXDATE"
properties contained within the
recurring component.
The "DTSTART" property defines the first instance in
the recurrence set.
The "DTSTART" property value SHOULD be synchronized with
the recurrence rule, if specified. The recurrence set
generated with a "DTSTART" property value not synchronized
with the recurrence rule is undefined.
The final recurrence set is generated by gathering all
of the start date/times generated by any of the specified
"RRULE" and "RDATE" properties, and then excluding any
start date/times
specified by "EXDATE" properties.
This implies that start date/times
specified by "EXDATE" properties
take precedence over those specified by inclusion properties
(i.e., "RDATE" and "RRULE"). Where duplicate instances are
generated by the "RRULE" and "RDATE" properties, only one
recurrence is considered. Duplicate instances are ignored.
The "DTSTART"
property
specified within the iCalendar object defines the first instance
of the recurrence.
In most cases, a "DTSTART" property of DATE-TIME value type
used with a recurrence rule, should be specified as a date
with local time and time zone reference to make sure all
the recurrence instances start at the same local time
regardless of time zone changes.
If the duration of the recurring component is specified
with the "DTEND" or "DUE" property, then the same exact
duration will apply to all the members of the generated
recurrence set. Else, if the duration of the recurring
component is specified with the "DURATION" property,
then the same nominal duration will apply to all the
members of the generated recurrence set and the exact
duration of each recurrence instance will depend on
its specific start time. For example, recurrence
instances of a nominal duration of one day will have
an exact duration of more or less than 24 hours on a day
where a time zone shift occurs.
The duration of a specific recurrence may be modified
in an exception component or simply by using an
"RDATE" property of PERIOD value type.
This property is defined by the following notation:
All examples assume the Eastern United States time zone.
Daily for 10 occurrences:
Daily until December 24, 1997:
Every other day - forever:
Every 10 days, 5 occurrences:
Everyday in January, for 3 years:
Weekly for 10 occurrences
Weekly until December 24, 1997
Every other week - forever:
Weekly on Tuesday and Thursday for 5 weeks:
Every other week on Monday, Wednesday and Friday until
December 24, 1997,
starting on
Monday,
September
1,
1997:
Every other week on Tuesday and Thursday, for 8 occurrences:
Monthly on the 1st Friday for ten occurrences:
Monthly on the 1st Friday until December 24, 1997:
Every other month on the 1st and last Sunday of the month
for 10 occurrences:
Monthly on the second to last Monday of the month for 6 months:
Monthly on the third to the last day of the month, forever:
Monthly on the 2nd and 15th of the month for 10 occurrences:
Monthly on the first and last day of the month for 10
occurrences:
Every 18 months on the 10th thru 15th of the month for 10
occurrences:
Every Tuesday, every other month:
Yearly in June and July for 10 occurrences:
Note: Since none of the BYDAY, BYMONTHDAY or
BYYEARDAY components are specified, the day is
gotten from "DTSTART"
Every other year on January, February, and March for 10
occurrences:
Every 3rd year on the 1st, 100th and 200th day for 10
occurrences:
Every 20th Monday of the year, forever:
Monday of week number 20 (where the default start of the week
is Monday), forever:
Every Thursday in March, forever:
Every Thursday, but only during June, July, and August, forever:
Every Friday the 13th, forever:
The first Saturday that follows the first Sunday of the month,
forever:
Every four years, the first Tuesday after a Monday in November,
forever (U.S. Presidential Election day):
The 3rd instance into the month of one of Tuesday, Wednesday
or Thursday, for the next 3 months:
The 2nd to last weekday of the month:
Every 3 hours from 9:00 AM to 5:00 PM on a specific day:
Every 15 minutes for 6 occurrences:
Every hour and a half for 4 occurrences:
Every 20 minutes from 9:00 AM to 4:40 PM every day:
An example where the days generated makes a difference because
of WKST:
changing only WKST from MO to SU, yields different results...
An example where an invalid date (i.e., February 30) is
ignored.
The following properties specify alarm information in calendar
components.
ACTION
This property defines the action to be invoked when an alarm
is triggered.
TEXT
IANA and non-standard
property parameters can be specified on this property.
This property MUST be specified once in a "VALARM" calendar
component.
Each "VALARM" calendar component has a particular type of
action associated with it. This property specifies the type
of action.
Applications MUST ignore alarms with x-name and iana-token
value they don't recognize.
This
property is defined by the following notation:
The following are examples of this property in a "VALARM"
calendar component:
REPEAT
This property defines the number of
times
the alarm should be
repeated, after the initial trigger.
INTEGER
IANA and non-standard
property parameters can be specified on this property.
This property can be specified in a "VALARM" calendar
component.
This property defines the number of time an alarm
should be repeated after its initial trigger.
If the alarm triggers more than once, then this property
MUST be specified along with the "DURATION" property.
This
property is defined by the following notation:
The following is an example of this property for an alarm
that repeats 4 additional times with a 5 minute delay after
the initial triggering of the alarm:
TRIGGER
This property specifies when an alarm will trigger.
The default value type is DURATION. The value type can be
set to a DATE-TIME value type, in which case the value MUST
specify a UTC formatted DATE-TIME value.
IANA, non-standard,
value data type, time zone identifier or trigger
relationship property parameters can be specified on this
property. The trigger relationship property parameter MUST
only be specified when the value type is "DURATION".
This property MUST be specified in the "VALARM" calendar
component.
This
property defines when
an
alarm will trigger. The default value type is DURATION,
specifying a relative time for the trigger of the alarm.
The default duration is relative to the start of an event
or to-do that the alarm is associated with. The duration
can be explicitly set to trigger from either the end or
the start of the associated event or to-do with the
"RELATED" parameter. A value of START will set the alarm to
trigger off the start of the associated event or to-do. A
value of END will set the alarm to trigger off the end of
the associated event or to-do.
Either a positive or negative duration may be specified for
the "TRIGGER" property. An alarm with a positive duration is
triggered after the associated start or end of the event or
to-do. An alarm with a negative duration is triggered before
the associated start or end of the event or to-do.
The "RELATED" property parameter is not valid if the value type
of the property is set to DATE-TIME (i.e., for an absolute
date and time alarm trigger). If a value type of DATE-TIME
is specified, then the property value MUST be specified in
the UTC time format. If an absolute trigger is specified on
an alarm for a recurring event or to-do, then the alarm will
only trigger for the specified absolute date/time, along with
any specified repeating instances.
If the trigger is set relative to START, then the "DTSTART"
property MUST be present in the associated "VEVENT" or "VTODO"
calendar component. If an alarm is specified for an event
with the trigger set relative to the END, then the "DTEND"
property or the
"DTSTART"
and
"DURATION
"
properties MUST be present in the associated "VEVENT" calendar
component. If the alarm is specified for a to-do with a trigger
set relative to the END, then either the "DUE" property or the
"DTSTART"
and "DURATION
"
properties MUST be present in the associated
"VTODO" calendar component.
Alarms specified in an event or to-do which is defined in terms
of a DATE value type will be triggered
relative to 00:00:00 of the user's configured time zone
on the specified date, or
relative to 00:00:00 UTC on the specified date
if no configured time zone can be found for the user.
For example, if
"DTSTART" is a DATE value set to 19980205
then the duration trigger will be relative
to
19980205T000000
America/New_York for a user configured with the America/New_York time zone.
This
property is defined by the following notation:
A trigger set 15 minutes prior to the start of the event or to-do.
A trigger set 5 minutes after the end of
an
event or
the due date of a
to-do.
A trigger set to an absolute date/time.
The following properties specify change management information in
calendar components.
CREATED
This property specifies the date and time that the calendar
information was created by the calendar user agent in the
calendar store.
Note: This is analogous to the creation date and time for a
file in the file system.
DATE-TIME
IANA and non-standard
property parameters can be specified on this property.
The property can be specified once in "VEVENT", "VTODO" or
"VJOURNAL" calendar components.
The value MUST be specified as a date with UTC time.
This property specifies the date and time that the
calendar information was created by the calendar user
agent in the calendar store.
This
property is defined by the following notation:
The following is an example of this property:
DTSTAMP
In the case of an iCalendar object that specifies
a "METHOD" property, this property specifies the
date and time that the instance of the iCalendar
object was created.
In the case of an iCalendar object that doesn't
specify a "METHOD" property, this property specifies
the date and time that the information associated
with the calendar component was last revised in
the calendar store.
DATE-TIME
IANA and non-standard
property parameters can be specified on this property.
This property MUST be included in the "VEVENT", "VTODO",
"VJOURNAL" or "VFREEBUSY" calendar components.
The value MUST be specified in the UTC time format.
This property is also useful to protocols such as
that have inherent latency issues with the delivery
of content. This property will assist in the proper
sequencing of messages containing iCalendar objects.
In the case of an iCalendar object that specifies
a "METHOD" property, this
property
differs from
the "CREATED" and "LAST-MODIFIED"
properties. These two properties are used to specify when
the particular calendar data in the calendar store was
created and last modified. This is different than when
the iCalendar object representation of the calendar
service information was created or last modified.
In the case of an iCalendar object that doesn't
specify a "METHOD" property, this property is
equivalent to the "LAST-MODIFIED" property.
This
property is defined by the following notation:
LAST-MODIFIED
This
property specifies the date and time that the information
associated with the calendar component was last revised in
the calendar store.
Note: This is analogous to the modification date and time
for a file in the file system.
DATE-TIME
IANA and non-standard
property parameters can be specified on this property.
This property can be specified in the "VEVENT", "VTODO",
"VJOURNAL" or "VTIMEZONE" calendar components.
The property value MUST be specified in the UTC time format.
This
property is defined by the following notation:
The following is
an
example
of this property:
SEQUENCE
This property defines the revision sequence number of the
calendar component within a sequence of revisions.
INTEGER
IANA and non-standard
property parameters can be specified on this property.
The property can be specified in "VEVENT", "VTODO" or
"VJOURNAL" calendar component.
When a calendar component is created, its sequence number is
zero (US-ASCII decimal 48). It is monotonically incremented
by the "Organizer's" CUA each time the "Organizer" makes
a significant revision to the calendar component.
The "Organizer" includes this property in an iCalendar object
that it sends to an "Attendee" to specify the current version
of the calendar component.
The "Attendee" includes this property in an iCalendar object
that it sends to the "Organizer" to specify the version of
the calendar component that the "Attendee" is referring to.
A change to the sequence number is not the mechanism
that an "Organizer" uses to request a response from the
"Attendees". The "RSVP" parameter on the "ATTENDEE" property
is used by the "Organizer" to indicate that a response from
the "Attendees" is requested.
Recurrence instances of a recurring component MAY have
different sequence numbers.
This property is defined by the following notation:
The following is an example of this property for a calendar
component that was just created by the "Organizer":
The following is an example of this property for a calendar
component that has been revised two different times by the
"Organizer":
The following properties specify information about a number of
miscellaneous features of calendar components.
An IANA registered property name
The default value type is TEXT.
The value type can be set to any value type.
Any parameter can be specified on this property.
This specification allows other properties registered
with IANA to be specified in any calendar components.
Compliant applications are expected to be able to parse
these other IANA registered properties but can ignore
them.
This property is defined by the following notation:
The following are examples of properties that might be
registered to IANA:
Any property name with a "X-" prefix
This class of property provides a framework for defining
non-standard properties.
The default value type is TEXT.
The value type can be set to any value type.
IANA, non-standard
and language property parameters can be specified
on this property.
This property can be specified in any calendar component.
The MIME Calendaring and Scheduling Content Type provides a
"standard mechanism for doing non-standard things". This
extension support is provided for implementers to "push
the envelope" on the existing version of the memo. Extension
properties are specified by property and/or property parameter
names that have the prefix text of "X-" (the two character
sequence: LATIN CAPITAL LETTER X character followed by
the
HYPHEN-MINUS
character). It is recommended that vendors
concatenate onto this sentinel another short prefix text to
identify the vendor. This will facilitate readability of the
extensions and minimize possible collision of names between
different vendors. User agents that support this content type
are expected to be able to parse the extension properties
and property parameters but can ignore them.
At present, there is no registration authority for names of
extension properties and property parameters. The value type
for this property is TEXT. Optionally, the value type can be
any of the other valid value types.
This
property is defined by the following notation:
The following might be the ABC vendor's extension for an
audio-clip form of subject property:
REQUEST-STATUS
This property defines the status code returned for a scheduling
request.
TEXT
IANA, non-standard
and language property parameters can be specified
on this property.
The property can be specified in "VEVENT", "VTODO", "VJOURNAL"
or "VFREEBUSY" calendar component.
This property is used to return status code information related
to the processing of an associated iCalendar object. The
value type for this property is TEXT.
The value consists of a short return status component, a
longer return status description component, and optionally a
status-specific data component. The components of the value
are separated by the SEMICOLON character (US-ASCII decimal 59).
The short return status is a PERIOD character (US-ASCII
decimal 46) separated
pair or
3-tuple of integers. For example,
"3.1" or
"3.1.1". The successive levels of integers provide for a
successive level of status code granularity.
The following are initial classes for the return status code.
Individual iCalendar object methods will define specific
return status codes for these classes. In addition, other
classes for the return status code may be defined using the
registration process defined later in this memo.
Short Return Status CodeLonger Return Status Description1.xx
Preliminary success. This class
of status code indicates that the
request has been initially
processed but that completion is pending.
2.xx
Successful. This class of status code
indicates that the request was completed
successfuly. However, the exact status code
can indicate that a fallback has been taken.
3.xx
Client Error. This class of status code
indicates that the request was not successful.
The error is the result of either a syntax or
a semantic error in the client formatted
request. Request should not be retried until
the condition in the request is corrected.
4.xx
Scheduling Error. This class of status code
indicates that the request was not successful.
Some sort of error occurred within the
calendaring and scheduling service, not
directly related to the request itself.
This
property is defined by the following notation:
The following are some possible examples of this property.
The COMMA and SEMICOLON separator characters in the property value
are BACKSLASH character escaped because they appear in a text value.
The following examples are provided as an informational source of
illustrative iCalendar objects consistent with this content type.
The following example specifies a three-day conference that begins at
2:30 P.M. UTC,
September 18, 1996 and end at
10:00 P.M. UTC,
September 20, 1996.
The following example specifies a group scheduled meeting that begin
at 8:30 AM EST on March 12, 1998 and end at 9:30 AM EST on March 12,
1998. The "Organizer" has scheduled the meeting with one or more
calendar users in a group. A time zone specification for Eastern
United States has been specified.
The following is an example of an iCalendar object passed in a MIME
message with a single body part consisting of a "text/calendar"
Content Type.
The following is an example of a to-do due on April 15, 1998. An audio
alarm has been specified to remind the calendar user at noon, the
day before the to-do is expected to be completed and repeat hourly,
four additional times. The to-do definition has been modified twice
since it was initially created.
The following is an example of a journal entry.
The following is an example of published busy time information. The
iCalendar object might be placed in the network resource
http://www.example.com/calendar/busytime/jsmith.ifb.
These recommended practices should be followed in order to assure
consistent handling of the following cases for an iCalendar object.
Content lines longer than 75 octets SHOULD be folded.
When the combination of the "RRULE" and "RDATE" properties
in a recurring component
produces multiple instances having the same start
DATE-TIME value,
they should be collapsed to, and considered as, a single instance.
If the "RDATE" property is specified as a PERIOD value the
duration of the recurrence instance will be the one specified
by the "RDATE" property, and not the duration of the
recurrence instance defined by the "DTSTART" property.
When a calendar user receives multiple requests for the same
calendar component (e.g., REQUEST for a "VEVENT" calendar
component) as a result of being on multiple mailing lists
specified by "ATTENDEE" properties in the request, they SHOULD
respond to only one of the requests. The calendar user SHOULD
also specify (using the "MEMBER" parameter of the "ATTENDEE"
property) which mailing list they are a member of.
An implementation can truncate a "SUMMARY" property value to 255
octets, but MUST NOT truncate the value in the middle
of a UTF-8 multi-octet sequence.
If seconds of the minute are not supported by an implementation,
then a value of "00" SHOULD be specified for the seconds
component in a time value.
"TZURL"
values SHOULD NOT be specified as a
file URI type. This URI form can be useful within an
organization, but is problematic in the Internet.
Some possible English values for "CATEGORIES" property include
"ANNIVERSARY", "APPOINTMENT", "BUSINESS", "EDUCATION",
"HOLIDAY", "MEETING", "MISCELLANEOUS", "NON-WORKING HOURS", "NOT
IN OFFICE", "PERSONAL", "PHONE CALL", "SICK DAY", "SPECIAL
OCCASION", "TRAVEL", "VACATION". Categories can be specified in
any registered language.
Some possible English values for "RESOURCES" property include
"CATERING", "CHAIRS", "COMPUTER PROJECTOR", "EASEL", "OVERHEAD
PROJECTOR", "SPEAKER PHONE", "TABLE", "TV", "VCR", "VIDEO
PHONE", "VEHICLE". Resources can be specified in any registered
language.
Applications MUST generate iCalendar stream in the UTF-8
charset and MUST accept iCalendar stream in the UTF-8 or
US-ASCII charset.
Because calendaring and scheduling information is very
privacy-sensitive, the protocol used for the transmission of
calendaring and scheduling information should have capabilities
to protect the information from possible threats, such as
eavesdropping, replay, message insertion, deletion, modification
and man-in-the-middle attacks.
As this document only defines the data format and media type
of text/calendar that is independent of any calendar service or
protocol, it is up to the actual protocol specifications such as
iTIP,
iMIP, and
CalDAV to describe the threats
that the above attacks present, as well as ways in which to
mitigate them.
The Calendaring and Scheduling Core Object Specification
is intended for use as a MIME content type.
To: ietf-types@iana.org
Subject: Registration of media type text/calendar
text
calendar
none
charset, method, component and optinfo
The "charset" parameter is defined in
for subtypes of the "text" media type. It is used to indicate
the charset used in the body part. The charset supported by
this revision of iCalendar is UTF-8. The use of any other
charset is deprecated by this revision of iCalendar; however
note that this revision requires that compliant applications
MUST accept iCalendar streams using either the UTF-8 or
US-ASCII charset.
The "method" parameter is used to convey the iCalendar
object method or transaction semantics for the calendaring
and scheduling information. It also is an identifier
for the restricted set of properties and values that the
iCalendar object consists of. The parameter is to be used
as a guide for applications interpreting the information
contained within the body part. It SHOULD NOT be used
to exclude or require particular pieces of information
unless the identified method definition specifically calls
for this behavior. Unless specifically forbidden by a
particular method definition, a text/calendar content
type can contain any set of properties permitted by the
Calendaring and Scheduling Core Object Specification.
The "method" parameter MUST be specified and MUST be set
to the same value as the "METHOD" component property of
the iCalendar objects of the iCalendar stream if and only
if the iCalendar objects in the iCalendar stream all have
a "METHOD" component property set to the same value.
The value for the "method" parameter is defined as follows:
The "component" parameter conveys the type of iCalendar
calendar component within the body part. If the iCalendar
object contains more than one calendar component type,
then multiple component parameters MUST be specified.
The value for the "component" parameter is defined as follows:
The "optinfo" parameter conveys optional information
about the iCalendar object within the body part. This
parameter can only specify semantics already specified by
the iCalendar object and that can be otherwise determined
by parsing the body part. In addition, the optional
information specified by this parameter MUST be consistent
with that information specified by the iCalendar object.
For example, it can be used to convey the "Attendee"
response status to a meeting request. The parameter value
consists of a string value.
The parameter can be specified multiple times.
The value for the "optinfo" parameter is defined as follows:
This media type can contain 8bit characters, so the use
of quoted-printable or base64 MIME Content-Transfer-Encodings
might be necessary when iCalendar objects are transferred
across protocols restricted to the 7bit repertoire. Note that
a text valued property in the content entity can also have
content encoding of special characters using a BACKSLASH
character (US-ASCII decimal 92) escapement technique. This
means that content values can end up encoded twice.
See .
This media type is intended to define a common format for
conveying calendaring and scheduling information between
different systems. It is heavily based on the earlier industry specification.
This specification.
This media type is designed for widespread use by Internet
calendaring and scheduling applications. In addition,
applications in the workflow and document management
area might find this content-type applicable. The
iTIP,
iMIP and
CalDAV Internet protocols
directly use this media type also.
None.
The file extension of "ics" is to be used to designate a file
containing (an arbitrary set of) calendaring and scheduling
information consistent with this MIME content type.
The file extension of "ifb" is to be used to designate a file
containing free or busy time information consistent with this
MIME content type.
The file type code of "iCal" is to be used in Apple MacIntosh
operating system environments to designate a file containing
calendaring and scheduling information consistent with this
MIME media type.
The file type code of "iFBf" is to be used in Apple MacIntosh
operating system environments to designate a file containing
free or busy time information consistent with this MIME
media type.
See the "Author's Address" section of this document.
COMMON
There are no restrictions on where this media type can be used.
See the "Author's Address" section of this document.
IETF
This section defines the process to register new or modified
iCalendar elements, that is, components, properties, parameters,
value data types, and values, with IANA.
The IETF will create a mailing list,
icalendar@ietf.org,
which can be used for public discussion of iCalendar elements
proposals prior to registration. Use of the mailing list
is strongly encouraged. The IESG will appoint a designated
expert who will monitor the
icalendar@ietf.org
mailing list and review registrations.
Registration of new iCalendar elements MUST be reviewed by
the designated expert and published in an RFC. A Standard
Tracks RFC is REQUIRED for the regisration of new value
data types that modify existing properties, as well as for
the registration of participation statuses values to
be used in "VEVENT" calendar components. A Standard Tracks
RFC is also REQUIRED for registration of iCalendar elements
that modify iCalendar elements previously documented in a
Standard Tracks RFC.
The registration procedure begins when a completed registration
template, defined in the sections below, is sent to
icalendar@ietf.org
and
iana@iana.org.
The designated expert is expected to tell IANA and the submitter
of the registration within two weeks whether the registration
is approved, approved with minor changes, or rejected with
cause. When a registration is rejected with cause, it can be
re-submitted if the concerns listed in the cause are addressed.
Decisions made by the designated expert can be appealed to the
IESG Applications Area Director, then to the IESG. They follow
the normal appeals procedure for IESG decisions.
A component is defined by completing the following template.
The name of the component.
The purpose of the component.
Give a short but clear description.
The ABNF for the component definition needs to be specified.
Any special notes about the component, how it is to be used,
etc.
One or more examples of instances of the component needs to
be specified.
A property is defined by completing the following template.
The name of the property.
The purpose of the property.
Give a short but clear description.
Any of the valid value types for the property value needs
to be specified. The default value type also needs to be
specified.
Any of the valid property parameters for the property MUST
be specified.
The calendar components that the property can appear in
MUST be specified.
Any special notes about the property, how it is to be used, etc.
The ABNF for the property definition needs to be specified.
One or more examples of instances of the property needs to
be specified.
A parameter is defined by completing the following template.
The name of the parameter.
The purpose of the parameter.
Give a short but clear description.
The ABNF for the parameter definition needs to be specified.
Any special notes about the parameter, how it is to be used,
etc.
One or more examples of instances of the parameter needs to
be specified.
A value data type is defined by completing the following template.
The name of the value type.
The purpose of the value type.
Give a short but clear description.
The ABNF for the value type definition needs to be specified.
Any special notes about the value type, how it is to be used, etc.
One or more examples of instances of the value type needs to
be specified.
A value is defined by completing the following template.
The value literal.
The purpose of the value.
Give a short but clear description.
The calendar properties and/or parameters that can
take this value needs to be specified.
One or more examples of instances of the value needs to
be specified.
The following is a fictitious example of a registration
of an iCalendar value:
TOP-SECRET
This value is used to specify the access classification
of top-secret calendar components.
This value can be used with the "CLASS" property.
The following is an example of this value used with
the "CLASS" property:
The IANA is requested to create and maintain the following
registries for iCalendar elements with pointers to
appropriate reference documents.
The following table is to be used to initialize the
components registry.
ComponentStatusReferenceVCALENDARCurrentRFCXXXX, VEVENTCurrentRFCXXXX, VTODOCurrentRFCXXXX, VJOURNALCurrentRFCXXXX, VFREEBUSYCurrentRFCXXXX, VTIMEZONECurrentRFCXXXX, VALARMCurrentRFCXXXX, STANDARDCurrentRFCXXXX, DAYLIGHTCurrentRFCXXXX,
The following table is to be used to initialize the
properties registry.
PropertyStatusReferenceCALSCALECurrentRFCXXXX, METHODCurrentRFCXXXX, PRODIDCurrentRFCXXXX, VERSIONCurrentRFCXXXX, ATTACHCurrentRFCXXXX, CATEGORIESCurrentRFCXXXX, CLASSCurrentRFCXXXX, COMMENTCurrentRFCXXXX, DESCRIPTIONCurrentRFCXXXX, GEOCurrentRFCXXXX, LOCATIONCurrentRFCXXXX, PERCENT-COMPLETECurrentRFCXXXX, PRIORITYCurrentRFCXXXX, RESOURCESCurrentRFCXXXX, STATUSCurrentRFCXXXX, SUMMARYCurrentRFCXXXX, COMPLETEDCurrentRFCXXXX, DTENDCurrentRFCXXXX, DUECurrentRFCXXXX, DTSTARTCurrentRFCXXXX, DURATIONCurrentRFCXXXX, FREEBUSYCurrentRFCXXXX, TRANSPCurrentRFCXXXX, TZIDCurrentRFCXXXX, TZNAMECurrentRFCXXXX, TZOFFSETFROMCurrentRFCXXXX, TZOFFSETTOCurrentRFCXXXX, TZURLCurrentRFCXXXX, ATTENDEECurrentRFCXXXX, CONTACTCurrentRFCXXXX, ORGANIZERCurrentRFCXXXX, RECURRENCE-IDCurrentRFCXXXX, RELATED-TOCurrentRFCXXXX, URLCurrentRFCXXXX, UIDCurrentRFCXXXX, EXDATECurrentRFCXXXX, EXRULEDeprecatedRFC2445,
Section 4.8.5.2RDATECurrentRFCXXXX, RRULECurrentRFCXXXX, ACTIONCurrentRFCXXXX, REPEATCurrentRFCXXXX, TRIGGERCurrentRFCXXXX, CREATEDCurrentRFCXXXX, DTSTAMPCurrentRFCXXXX, LAST-MODIFIEDCurrentRFCXXXX, SEQUENCECurrentRFCXXXX, REQUEST-STATUSCurrentRFCXXXX,
The following table is to be used to initialize the
parameters registry.
ParameterStatusReferenceALTREPCurrentRFCXXXX, CNCurrentRFCXXXX, CUTYPECurrentRFCXXXX, DELEGATED-FROMCurrentRFCXXXX, DELEGATED-TOCurrentRFCXXXX, DIRCurrentRFCXXXX, ENCODINGCurrentRFCXXXX, FMTTYPECurrentRFCXXXX, FBTYPECurrentRFCXXXX, LANGUAGECurrentRFCXXXX, MEMBERCurrentRFCXXXX, PARTSTATCurrentRFCXXXX, RANGECurrentRFCXXXX, RELATEDCurrentRFCXXXX, RELTYPECurrentRFCXXXX, ROLECurrentRFCXXXX, RSVPCurrentRFCXXXX, SENT-BYCurrentRFCXXXX, TZIDCurrentRFCXXXX, VALUECurrentRFCXXXX,
The following table is to be used to initialize the
value data types registry.
Value Data TypeStatusReferenceBINARYCurrentRFCXXXX, BOOLEANCurrentRFCXXXX, CAL-ADDRESSCurrentRFCXXXX, DATECurrentRFCXXXX, DATE-TIMECurrentRFCXXXX, DURATIONCurrentRFCXXXX, FLOATCurrentRFCXXXX, INTEGERCurrentRFCXXXX, PERIODCurrentRFCXXXX, RECURCurrentRFCXXXX, TEXTCurrentRFCXXXX, TIMECurrentRFCXXXX, URICurrentRFCXXXX, UTC-OFFSETCurrentRFCXXXX,
The following table is to be used to initialize the
calendar user types registry.
Calendar User TypeStatusReferenceINDIVIDUALCurrentRFCXXXX, GROUPCurrentRFCXXXX, RESOURCECurrentRFCXXXX, ROOMCurrentRFCXXXX, UNKNOWNCurrentRFCXXXX,
The following table is to be used to initialize the
free/busy time types registry.
Free/Busy Time TypeStatusReferenceFREECurrentRFCXXXX, BUSYCurrentRFCXXXX, BUSY-UNAVAILABLECurrentRFCXXXX, BUSY-TENTATIVECurrentRFCXXXX,
The following table is to be used to initialize the
participation statuses registry.
Participant StatusStatusReferenceNEEDS-ACTIONCurrentRFCXXXX, ACCEPTEDCurrentRFCXXXX, DECLINEDCurrentRFCXXXX, TENTATIVECurrentRFCXXXX, DELEGATEDCurrentRFCXXXX, COMPLETEDCurrentRFCXXXX, IN-PROCESSCurrentRFCXXXX,
The following table is to be used to initialize the property
parameters registry.
Relationship TypeStatusReferenceCHILDCurrentRFCXXXX, PARENTCurrentRFCXXXX, SIBLINGCurrentRFCXXXX,
The following table is to be used to initialize the
participation roles registry.
Role TypeStatusReferenceCHAIRCurrentRFCXXXX, REQ-PARTICIPANTCurrentRFCXXXX, OPT-PARTICIPANTCurrentRFCXXXX, NON-PARTICIPANTCurrentRFCXXXX,
The following table is to be used to initialize the
actions registry.
ActionStatusReferenceAUDIOCurrentRFCXXXX, DISPLAYCurrentRFCXXXX, EMAILCurrentRFCXXXX, PROCEDUREDeprecatedRFC2445,
Section 4.8.6.1
The following table is to be used to initialize the
classifications registry.
ClassificationStatusReferencePUBLICCurrentRFCXXXX, PRIVATECurrentRFCXXXX, CONFIDENTIALCurrentRFCXXXX,
No values are defined in this document for the
"METHOD" property.
The editor of this document wish to thank Frank Dawson and
Derik Stenerson, the original authors of RFC2445, as well as
the following individuals who have participated in the drafting,
review and discussion of this memo:
Joe Abley,
Hervey Allen,
Steve Allen,
Jay Batson,
Oliver Block,
Stephane Bortzmeyer,
Chris Bryant,
Tantek Celik,
Mark Crispin,
Cyrus Daboo,
Mike Douglass,
Andrew N. Dowden,
Lisa Dusseault,
Lars Eggert,
Gren Eliot,
Pasi Eronen,
Ben Fortuna,
Ned Freed,
Neal Gafter,
Ted Hardie,
Tim Hare,
Jeffrey Harris,
Helge Hess,
Paul B. Hill,
Thomas Hnetila,
Russ Housley,
Leif Johansson,
Ciny Joy,
Bruce Kahn,
Reinhold Kainhofer,
Martin Kiff,
Patrice Lapierre,
Eliot Lear,
Michiel van Leeuwen,
Jonathan Lennox,
Jeff McCullough,
Bill McQuillan,
Alexey Melnikov,
Aki Niemi,
John W. Noerenberg II,
Chuck Norris,
Mark Paterson,
Simon Pilette,
Arnaud Quillaud,
Robert Ransdell,
Julian F. Reschke,
Caleb Richardson,
Sam Roberts,
Dan Romascanu,
Mike Samuel,
George Sexton,
Nigel Swinson,
Clint Talbert,
Simon Vaillancourt,
Magnus Westerlund,
and Sandy Wills.
The editor would also like to thank the Calendaring and Scheduling
Consortium for advice with this specification, and for organizing
interoperability testing events to help refine it.
The mailto URL schemeInternet Mail ConsortiumXerox CorporationNetscape Communications Corp.
Applications
Uniform Resource Identifier (URI): Generic Syntax
World Wide Web ConsortiumDay SoftwareAdobe Systems Incorporated
Applications
Tags for Identifying LanguagesMultipurpose Internet Mail
Extensions (MIME) Part One:
Format of Internet Message
BodiesInnosoft International, Inc.First Virtual HoldingsMultipurpose Internet Mail Extensions
(MIME) Part Two: Media TypesInnosoft International, Inc.First Virtual HoldingsKey words for use in RFCs to Indicate
Requirement LevelsHarvard University
General
keywordAugmented BNF for Syntax Specifications: ABNFUTF-8, a transformation format of ISO 10646Media Type Specifications and Registration ProceduresThe Base16, Base32, and Base64 Data Encodings
Data elements and interchange formats --
Information interchange --
Representation of dates and times
International Organization for Standardization
Information Technology_SGML Support Facilities -- Registration
Procedures for Public Text Owner Identifiers, Second EditionInternational Organization for StandardizationUniform Resource Locators (URL)CERN, World-Wide Web projectXerox PARCUniversity of Minnesota, Computer and Information
ServicesA MIME
Content-Type
for
Directory
InformationNetscape Communications Corp.Netscape Communications Corp.Lotus Development Corporation
Applications
Content-ID and
Message-ID Uniform
Resource LocatorsThe "data" URL schemeXerox Palo Alto Research CentervCard MIME Directory ProfileLotus Development CorporationNetscape Communications Corp.
Applications
MIMEaudiocontent-typedirectorymultipurpose internet mail extensionsHypertext Transfer Protocol -- HTTP/1.1Department of Information and Computer ScienceWorld Wide Web ConsortiumCompaq Computer CorporationWorld Wide Web ConsortiumXerox CorporationMicrosoft CorporationWorld Wide Web ConsortiumHTTP Over TLSLightweight Directory Access Protocol (LDAP): Uniform
Resource LocatorCalendaring Extensions to WebDAV (CalDAV)Apple Inc.Oracle CorporationCommerceNetiCalendar Transport-Independent Interoperability Protocol
(iTIP)iCalendar Message-Based Interoperability Protocol(iMIP)Sources for Time Zone and Daylight Saving Time Data
[Note to RFC Editor: Change "A. Olson" to "A.D. Olson".]
vCalendar: The Electronic Calendaring and Scheduling Exchange
FormatInternet Mail Consortium
This appendix contains a list of changes that have been made in
the Internet Calendaring and Scheduling Core Object Specification
from RFC 2445.
The "DTSTART" property SHOULD be synchronized with
the recurrence rule, if specified.
The "RRULE" property SHOULD NOT occur more than once
in a component.
The BYHOUR, BYMINUTE and BYSECOND rule parts MUST NOT
be specified in the "RRULE" property when the "DTSTART"
property is specified as a DATE value.
The value type of the "DTEND" or "DUE" properties MUST
match the value type of "DTSTART" property.
The "DURATION" property can no longer appear in
"VFREEBUSY" components.
The "DTSTART" and "DTEND" properties are no longer
required to be specified as date with local time
and time zone reference when used with a recurrence rule.
The "EXRULE" property can no longer be specified in a component.
The "THISANDPRIOR" value can no longer be used with the "RANGE"
parameter.
The "PROCEDURE" value can no longer be used with the "ACTION"
property.
The value type RECUR no longer allow multiple values to
be specified by a COMMA (US-ASCII decimal 44) character
separated list of values.
x-name rule parts can no longer be specified in properties
of RECUR value type (e.g., "RRULE"). x-param can be used on
RECUR value type properties instead.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-10.changes.html.
Addressed IESG evaluation comments and discusses.
Clarified that the "RECURRENCE-ID" property MUST have the
same value type as the "DTSTART" property contained within the
recurring component and MUST be specified as a date with local
time if and only if the "DTSTART" property contained within
the recurring component is specified as a date with local time.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-09.changes.html.
Issue 60: Clarified that multi-valued properties MUST NOT
be used to specify multiple language variants of the same
value.
Issue 67: Forbid the use of the "DURATION" property in
"VFREEBUSY" components.
AD-Issue 1: Added note on most commonly used URI schemes
for the "ALTREP" parameter.
AD-Issue 2: Added recommendation on the URI schemes to use
for the "DIR" parameter.
AD-Issue 4: Added recommendation for calendar applications
that support importing iCalendar objects.
iTIP-APPS-Issue 1: Allowed "DTSTART" to be OPTIONAL for iTIP.
iTIP-APPS-Issue 2: Fixed time zone example.
iTIP-APPS-Issue 3: Clarified that recurrence instances MAY
have different sequence numbers.
iTIP-APPS-Issue 4: Clarified description of the "INTERVAL"
rule part.
Modified TSAFE-CHAR to allow HTAB (US-ASCII decimal 9)
in TEXT values.
Few editorial changes.
Added names to the Acknowledgments section.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-08.changes.html.
Issue 48: Revert the change to deprecate the "RANGE" parameter.
Only the value "THISANDPRIOR" is deprecated.
Issue 81: BYSETPOS: Clarify that "a set" starts at the
beginning of the interval defined by the FREQ rule part.
Chair Review: Changed requirement to handle unrecognized
CUTYPE values.
Chair Review: Changed requirement to handle unrecognized
VALUE data types.
Chair Review: Removed requirements for "DELEGATED-TO" and
"DELEGATED-FROM" to be specified as mailto URI.
Chair Review: Added note about alarms from untrusted sources.
Chair Review: Added text to clarify the structure of the
document.
Chair Review: Added forward reference to the section
covering BACKSLASH character encoding.
Removed the text that specifies when the sequence number
MUST be incremented. Text will be added to rfc2446bis.
Removed normative reference to RFC2822.
Changed reference of RFC4234 to RFC5234.
Few editorial changes.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-07.changes.html.
Issue 8: Clarified how to compute the exact duration of a
nominal duration.
Issue 10: Added new examples for "VEVENT" and "VTODO" to
demonstrate that end times are always non-inclusive, that
is, even end times specified as DATE values.
Issue 11: Added a table that shows the dependency of
BYxxx rule part expand or limit behaviour on the FREQ
value in the rule.
Issue 19: Removed section "Registration of Content Type Elements".
Added registration templates in IANA Considerations section.
Specified how applications should treat x-name and x-token they
don't recognize.
Issue 65: Removed 3rd recommended practice. Added new
requirements to require "DTEND" and "DUE" to be a local
date time if and only if "DTSTART" is a local date time.
Issue 68: Clarified handling of date-times that fall in
time discontinutities.
Issue 69: Clarified handling of recurrence instances that
fall in time discontinutities
Issue 71: Clarified handling of leap seconds.
Issue 75: Clarified that the "RDATE" property MUST be
specified as a local DATE-TIME value in "VTIMEZONE"
sub-components.
Issue 76: Clarified that the value type of the "DTEND"
property MUST be the same as the "DTSTART" property.
Issue 77: Clarified that the value type of the "DUE"
property MUST be the same as the "DTSTART" property.
Issue 79: Clarified that "DTSTART" always specify an onset
date-time of an observance and that its value does not need
to be repeated in an "RDATE" property.
Issue 80: Rewrote Security Considerations section.
Issue 81: Clarified the meaning of "the set of events specified
by the rule" in the description of the BYSETPOS rule part.
Modified Abstract section.
Moved text of section 2.3 International Considerations
at the end of sectino 2.1 Formatting Conventions.
Added Internationalization Considerations section.
Modified the description of the following properties:
"ATTACH", "COMMENT", "COMPLETED", "CREATED" "DTSTAMP"
"DUE", and "REPEAT".
Clarified some differences with ISO 8601.
Updated reference to CalDAV and ISO 8601.
Updated section "Differences from RFC 2445":
added new restrictions and added list of removed
restrictions.
Numerous editorial changes.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-06.changes.html.
Issue 19: Defined new IANA registries. [Work in progress];
Issue 23: Clarified that the UNTIL rule part MUST specify
a value of the same type as the value specified by "DTSTART";
Issue 27: Clarified how the duration of generated
recurrence instances is determined;
Issue 35: Further clarified the description of the
"LANGUAGE" property;
Issue 42: Removed the restriction on the values allowed
for the "ACTION" property in the the "VALARM" component;
Issue 47: Clarified that alarm triggers relative to a DATE
value type needs to be triggered to 00:00:00 of the user's
configured time zone;
Issue 56: Added a note to specify that FREQ MUST be
specified as the first rule part in generated iCalendar
applications, but MUST be accepted in any order to
ensure backward compatibility. The rest of the RECUR
value type ABNF has been further simplified;
Issue 59: Clarified the default duration of "VEVENT"
components specified with a "DTSTART" property of
DATE value type;
Issue 61: Modified all the property ABNFs to allow
iana-param in addition to x-param. Also modified the
component ABNFs to allow iana-prop in addition to
x-prop. [Work in progress];
Issue 62: Removed the text that lead to believe that
the "RECURRENCE-ID" of a specific recurrence instance
might change;
Issue 64: Clarified that REQUEST-STATUS only allows
pairs (1.1) and 3-tuples (1.1.1).
Issue 65: Clarified that a different time zone may be used
by "DTSTART" and "DTEND", and "DTSTART" and "DUE" when
specified as date with local time and time zone reference.
[Work in progress];
Issue 66: Clarified that if the "RDATE" property is specified
as a PERIOD, its duration has precedence over the duration
of the recurrence instance defined by the "DTSTART" property;
Issue 72: Removed the requirement that a "VTIMEZONE"
calendar component MUST be present if the iCalendar object
contains an RRULE that generates dates on both sides of
a time zone shift;
Issue 73: Clarified that the "TZID" must be unique in the
scope of an iCalendar object only;
Issue 74: Deprecated the "PROCEDURE" value for the
"ACTION" property;
Issue 78: Fixed the text to specify that "TZOFFSETFROM"
and not "TZOFFSETTO" must be used with "DTSTART" when
generating the onset date-time values from the "RRULE"
in a "VTIMEZONE" component;
Clarified that the "DTSTART" property MUST be specified
in a "VTODO" component when the "DURATION" property is
specified;
Started to update the time zone information / examples;
Numerous editorial changes.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-05.changes.html.
Fixed ABNF with references in .txt version of the draft;
Numerous editorial changes;
Clarified that normative statements in ABNF
comments should be considered as normative;
Removed notes talking of character sets other
than US-ASCII and UTF-8;
Renamed CTL to CONTROL to avoid conflict with the CTL
rule defined in RFC4234;
Removed ABNF rules defined in RFC4234;
Changed the partstatparam ABNF rule for clarity;
Clarified the purpose of negative durations;
Added informational references to
RFC 2392 (CID URL) and RFC 4516 (LDAP URL).
Updated TZDB reference.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-04.changes.html.
Issue 16:
Clarified that recurrence instances, generated by a recurrence rule,
with an invalid date or nonexistent local time must be ignored and
not counted as part of the recurrence set.
Issue 26:
Clarified how to handle the BYHOUR, BYMINUTE and BYSECOND rule
parts when "DTSTART" is a DATE value.
Issue 28:
Removed the MUST requirement to specify the "RDATE" property
whenever the duration of a recurrence instance is modified.
Issue 29:
Clarified that the "DTSTART" property is REQUIRED in all
types of recurring components.
Issue 32:
Introduced the notion of an "iCalendar stream" to make it explicit
when we are refering to a "single iCalendar object" or a "sequence
of iCalendar objects".
Issue 34:
Clarified what should be done with the "method" parameter when
the iCalendar stream is a sequence of iCalendar objects.
Issue 40:
Changed to fbprop ABNF rule to specify that the "DTSTAMP" and
the "UID" properties are REQUIRED in "VFREEBUSY" components.
Issue 43:
Removed the MUST requirement to specify the "DTSTART" and the
"DTEND" properties as local time in recurring components, but
added a note that in most cases this is the right thing to do.
Issue 44:
Changed the x-prop ABNF to allow any parameters on non-standard
properties.
Issue 46:
Simplified the tzprop, audioprop, dispprop, emailprop, and
procprop ABNF rules by removing the number of required
properties in front of the "*".
Issue 48:
Deprecated the "RANGE" parameter.
Issue 51:
Clarified implicit duration of day events with no "DTEND" nor
"DURATION" property.
Issue 52:
Removed x-name from the "recur" rule part definition.
It should be sufficient to allow xparam on properties of
RECUR value type.
Issue 53:
Updated the NON-US-ASCII ABNF rule for UTF-8.
Issue 56:
Changed the "recur" ABNF rule to allow rule parts to be
specified in any order.
Issue 57:
Specified that the "DURATION" property MUST be specified as a
"dur-day" or "dur-week" value when the "DTSTART" is a DATE.
Issue 58:
Changed the jourprop ABNF rule to allow the "DESCRIPTION"
property to occur more than once.
Numerous editorial changes.
Changed reference to RFC 4646 for Language-Tag.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-03.changes.html.
Numerous editorial changes.
Specified that "DTSTART" should match the pattern of "RRULE"
and is always part of the "COUNT".
Specified "RRULE" should not occur more than once in
recurring components.
Deprecated "EXRULE".
Fixed all ABNF errors reported by Bill Fenner's ABNF
parsing web service available at:
http://rtg.ietf.org/~fenner/abnf.cgi.
Changed reference to RFC 4648 for Base64 encoding.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-02.changes.html.
Numerous editorial changes including the typos listed
in the "RFC2445 Errata":
http://www.rfc-editor.org/cgi-bin/errataSearch.pl?rfc=2445&
and in the "RFC2445 Issues List":
http://www.softwarestudio.org/iCal/2445Issues.html.
Clarified line folding requirements.
Clarified charset requirements.
Clarified line limits requirements.
Clarified on the use of the "LANGUAGE" parameter.
Fixed the eventprop, todoprop and jourprop ABNF rules with
respect to required properties.
Fixed all the examples to use RFC2606-compliant FQDNs.
Fixed the Content-ID URLs in the examples.
Fixed the LDAP URLs in the examples.
Moved multiple references in the Informative References section.
Updated the Acknowledgments section.
A detailed list of changes is available at the following page:
http://tools.ietf.org/wg/calsify/draft-ietf-calsify-rfc2445bis/draft-ietf-calsify-rfc2445bis-01.changes.html.
Numerous editorial changes (typos, errors in examples, etc.).
Fixed invalid media types in examples.
Fixed the "DTSTAMP" values in the examples.
Moved media type registration in a separate IANA Consideration
section.
Added Internationalization Considerations section.
Added Security Considerations section.
Updated the Acknowledgments section.