| RFC 2445 | |
| MUST/MUST NOT | |
| line number | Text with Condition |
| 354: | is used, appropriate code-point from that character set MUST be |
| 405: | Specification. The "method" parameter MUST be the same value as that |
| 407: | If one is present, the other MUST also be present. |
| 417: | MUST be specified. |
| 428: | the optional information specified by this parameter MUST be |
| 649: | When parsing a content line, folded lines MUST first be unfolded |
| 676: | ; When parsing a content line, folded lines MUST first |
| 779: | list of values MUST be separated by a COMMA character (US-ASCII |
| 786: | structured property values MUST have their value parts separated by a |
| 790: | in a list of property parameters MUST be separated by a SEMICOLON |
| 794: | COMMA character MUST be placed in quoted text. |
| 829: | content information MUST specify the "ENCODING" property parameter. |
| 831: | MUST be referenced by a uniform resource identifier (URI). |
| 866: | character separators MUST be specified as quoted-string text values. |
| 867: | Property parameter values MUST NOT contain the DOUBLE-QUOTE (US-ASCII |
| 940: | specifying this parameter MUST also include a value that reflects the |
| 942: | parameter values MUST each be specified in a quoted-string. |
| 1053: | property. The value MUST be a MAILTO URI as defined in [RFC 1738]. |
| 1054: | The individual calendar address parameter values MUST each be |
| 1078: | to-do by the calendar user specified by the property. The value MUST |
| 1080: | address parameter values MUST each be specified in a quoted-string. |
| 1110: | values MUST each be specified in a quoted-string. |
| 1144: | encoding parameter MUST be specified with the value |
| 1185: | of content associated with the resource. The parameter value MUST be |
| 1297: | parameter values MUST each be specified in a quoted-string. |
| 1368: | a group scheduled "VEVENT", "VTODO" or "VJOURNAL". The values MUST |
| 1579: | property. The parameter value MUST be a MAILTO URI as defined in [RFC |
| 1580: | 1738]. The individual calendar address parameter values MUST each be |
| 1608: | Description: The parameter MUST be specified on the "DTSTART", |
| 1618: | component MUST be specified for each unique "TZID" parameter value |
| 1621: | The parameter MUST be specified on properties with a DATE-TIME value |
| 1641: | The TZID property parameter MUST NOT be applied to DATE-TIME or TIME |
| 1696: | property value. The property values MUST be of a single value type. |
| 1703: | this parameter MUST be specified. |
| 1721: | valid types, then it MUST be explicitly specified with the "VALUE" |
| 1743: | Description: Property values with this value type MUST also include |
| 1745: | is, all inline binary data MUST first be character encoded using the |
| 1801: | email transport address for a calendar user, the value MUST be a |
| 1878: | The form of date and time with UTC offset MUST NOT be used. For |
| 1915: | time zone reference MUST be specified. |
| 1930: | The TZID property parameter MUST NOT be applied to DATE-TIME |
| 1961: | A time value MUST ONLY specify 60 seconds when specifying the |
| 2086: | ; time consisting of a start and end. The start MUST be before the |
| 2100: | period. The start of the period MUST be before the end of the period. |
| 2141: | ; but UNTIL and COUNT MUST NOT occur in the same 'recur' |
| 2147: | ; but MUST NOT occur more than once |
| 2240: | ordered in any particular sequence. Individual rule parts MUST only |
| 2244: | part MUST be specified in the recurrence rule. Valid values include |
| 2266: | as a date-time value, then it MUST be specified in an UTC time |
| 2348: | 366 or -366 to -1. It MUST only be used in conjunction with another |
| 2463: | An intentional formatted text line break MUST only be included in a |
| 2473: | values, they MUST be escaped with a BACKSLASH character. A BACKSLASH |
| 2474: | character (US-ASCII decimal 92) in a "TEXT" property value MUST be |
| 2476: | "TEXT" property value MUST be escaped with a BACKSLASH character |
| 2478: | value MUST be escaped with a BACKSLASH character (US-ASCII decimal |
| 2533: | in the minute (i.e., values 0-60). The seconds value of 60 MUST only |
| 2540: | The form of time with UTC offset MUST NOT be used. For example, the |
| 2576: | time zone reference MUST be specified. |
| 2592: | The TZID property parameter MUST NOT be applied to TIME properties |
| 2645: | When a property parameter value is a URI value type, the URI MUST be |
| 2677: | Description: The PLUS SIGN character MUST be specified for positive |
| 2698: | line and last line of the iCalendar object MUST contain a pair of |
| 2764: | ; but MUST NOT occur more than once |
| 2769: | ; but MUST NOT occur more than once |
| 2801: | An iCalendar object MUST include the "PRODID" and "VERSION" calendar |
| 2802: | properties. In addition, it MUST include at least one calendar |
| 2829: | ; but MUST NOT occur more than once |
| 2846: | ; MUST NOT occur in the same 'eventprop' |
| 2873: | MUST be specified as a DATE value also. The anniversary type of |
| 2969: | ; but MUST NOT occur more than once |
| 2978: | ; MUST NOT occur in the same 'todoprop' |
| 3043: | ; but MUST NOT occur more than once |
| 3138: | ; but MUST NOT occur more than once |
| 3273: | ; 'tzid' is required, but MUST NOT occur more |
| 3279: | but MUST NOT occur more than once |
| 3290: | ; one of 'standardc' or 'daylightc' MUST occur |
| 3319: | ; but MUST NOT occur more than once |
| 3391: | object. In this situation, each "VTIMEZONE" MUST represent a unique |
| 3404: | The "VTIMEZONE" calendar component MUST be present if the iCalendar |
| 3410: | such a RRULE. In addition, if a RRULE is present, there MUST be valid |
| 3413: | The "VTIMEZONE" calendar component MUST include the "TZID" property |
| 3415: | standard or daylight component MUST include the "DTSTART", |
| 3418: | An individual "VTIMEZONE" calendar component MUST be specified for |
| 3478: | this usage MUST be specified as a local DATE-TIME value. |
| 3519: | "UNTIL" recurrence rule parameter MUST be used to specify the |
| 3522: | pattern). It MUST be specified in UTC time. |
| 3524: | - The "DTSTART" and the "TZOFFSETTO" properties MUST be used |
| 3530: | "RDATE" in this usage MUST be specified as a local DATE-TIME value in |
| 3690: | ; but MUST NOT occur more than once |
| 3695: | ; and MUST NOT occur more than once each, |
| 3696: | ; but if one occurs, so MUST the other |
| 3701: | ; but MUST NOT occur more than once |
| 3717: | ; but MUST NOT occur more than once |
| 3722: | ; and MUST NOT occur more than once each, |
| 3723: | ; but if one occurs, so MUST the other |
| 3747: | ; but MUST NOT occur more than once |
| 3757: | ; and MUST NOT occur more than once each, |
| 3758: | ; but if one occurs, so MUST the other |
| 3774: | ; but MUST NOT occur more than once |
| 3779: | ; and MUST NOT occur more than once each, |
| 3780: | ; but if one occurs, so MUST the other |
| 3793: | ; and MUST NOT occur more than once |
| 3809: | The "VALARM" calendar component MUST include the "ACTION" and |
| 3814: | one "ATTACH" property, which MUST point to a sound resource, which is |
| 3817: | When the action is "DISPLAY", the alarm MUST also include a |
| 3821: | When the action is "EMAIL", the alarm MUST include a "DESCRIPTION" |
| 3830: | When the action is "PROCEDURE", the alarm MUST include one and only |
| 3831: | one "ATTACH" property, which MUST point to a procedure resource, |
| 3834: | The "VALARM" calendar component MUST only appear within either a |
| 3857: | "DTSTART" property MUST be present in the associated event or to-do. |
| 3859: | "END" of the event, either the "DTEND" property MUST be present, or |
| 3860: | the "DTSTART" and "DURATION" properties MUST both be present. In an |
| 3862: | the to-do, either the "DUE" property MUST be present, or the |
| 3863: | "DTSTART" and "DURATION" properties MUST both be present. |
| 3866: | definition of an alarm with a repeating trigger MUST include both the |
| 3871: | initial triggering of the alarm. Both of these properties MUST be |
| 3887: | MUST specify one and only one of these values. |
| 3890: | MUST specify an audio sound resource. The intention is that the sound |
| 3913: | "DESCRIPTION" property of the "VALARM" calendar component MUST be |
| 3914: | used as the body text of the message, and the "SUMMARY" property MUST |
| 3919: | component MUST specify a procedure or program that is intended to be |
| 4057: | property MUST be the same as the Content-Type "method" parameter |
| 4060: | parameter is specified, then the other MUST also be specified. |
| 4075: | scheduling transaction MUST NOT be assumed. In such cases, the |
| 4105: | Conformance: The property MUST be specified once in an iCalendar |
| 4153: | Conformance: This property MUST be specified by an iCalendar object, |
| 4154: | but MUST only be specified once. |
| 4228: | ; but MUST NOT occur more than once |
| 4284: | ; but MUST NOT occur more than once |
| 4384: | ; but MUST NOT occur more than once |
| 4446: | ; but MUST NOT occur more than once |
| 4469: | MUST attend this meeting.\n RSVP to team leader. |
| 4484: | Value Type: FLOAT. The value MUST be two SEMICOLON separated FLOAT |
| 4499: | MUST accept values of this precision and MAY truncate values of |
| 4607: | ; but MUST NOT occur more than once |
| 4784: | ; but MUST NOT occur more than once |
| 4919: | ; but MUST NOT occur more than once |
| 4954: | Description: The date and time MUST be in a UTC format. |
| 4991: | defines the date and time by which the event ends. The value MUST be |
| 4996: | MUST be specified in the UTC time format. The value MUST be later in |
| 5006: | ; but MUST NOT occur more than once |
| 5031: | ;Value MUST match value type |
| 5055: | Description: The value MUST be a date/time equal to or after the |
| 5064: | ; but MUST NOT occur more than once |
| 5087: | ;Value MUST match value type |
| 5099: | Value Type: The default value type is DATE-TIME. The time value MUST |
| 5117: | MUST be specified in UTC time. |
| 5122: | in "VTIMEZONE" calendar components and MUST be specified as a local |
| 5139: | ; but MUST NOT occur more than once |
| 5154: | ;Value MUST match value type |
| 5214: | Value Type: PERIOD. The date and time values MUST be in an UTC time |
| 5228: | time MUST be a UTC time format. |
| 5255: | ; but MUST NOT occur more than once |
| 5267: | ;Time value MUST be in the UTC time format. |
| 5347: | Conformance: This property MUST be specified in a "VTIMEZONE" |
| 5430: | ; but MUST NOT occur more than once |
| 5472: | Conformance: This property MUST be specified in a "VTIMEZONE" |
| 5478: | MUST only be specified in a "VTIMEZONE" calendar component. A |
| 5479: | "VTIMEZONE" calendar component MUST include this property. The |
| 5510: | Conformance: This property MUST be specified in a "VTIMEZONE" |
| 5604: | Conformance: This property MUST be specified in an iCalendar object |
| 5605: | that specifies a group scheduled calendar entity. This property MUST |
| 5614: | Description: The property MUST only be specified within calendar |
| 5641: | component. They MUST not be specified in an "ATTENDEE" property in a |
| 5646: | A recipient delegated a request MUST inherit the RSVP and ROLE values |
| 5659: | ; but MUST NOT occur more than once |
| 5763: | ; but MUST NOT occur more than once |
| 5823: | Conformance: This property MUST be specified in an iCalendar object |
| 5824: | that specifies a group scheduled calendar entity. This property MUST |
| 5826: | a calendar user's busy time. This property MUST NOT be specified in |
| 5864: | ; but MUST NOT occur more than once |
| 5934: | value MUST be the calendar date for the recurrence instance. |
| 5964: | ; but MUST NOT occur more than once |
| 5984: | ;Value MUST match value type |
| 6050: | ; but MUST NOT occur more than once |
| 6097: | MUST point to the same resource. |
| 6121: | Conformance: The property MUST be specified in the "VEVENT", "VTODO", |
| 6124: | Description: The UID itself MUST be a globally unique identifier. The |
| 6125: | generator of the identifier MUST guarantee that the identifier is |
| 6163: | deletion requests. Calendaring and scheduling applications MUST |
| 6169: | Implementations MUST be able to receive and persist values of at |
| 6233: | "DTSTART". However, in such cases the original "DTSTART" date MUST |
| 6245: | ; but MUST NOT occur more than once |
| 6266: | ;Value MUST match value type |
| 6317: | "DTSTART". However, in such cases the original "DTSTART" date MUST |
| 6399: | ; but MUST NOT occur more than once |
| 6412: | ;Value MUST match value type |
| 6483: | the "DTSTART" and "DTEND" properties MUST be specified in local time |
| 6484: | and the appropriate set of "VTIMEZONE" calendar components MUST be |
| 6490: | specific recurrences MUST be explicitly specified using the "RDATE" |
| 6945: | Conformance: This property MUST be specified once in a "VALARM" |
| 6993: | MUST be specified along with the "DURATION" property. |
| 7016: | set to a DATE-TIME value type, in which case the value MUST specify a |
| 7022: | parameter MUST only be specified when the value type is DURATION. |
| 7024: | Conformance: This property MUST be specified in the "VALARM" calendar |
| 7055: | property value MUST be specified in the UTC time format. If an |
| 7061: | MUST be present in the associated "VEVENT" or "VTODO" calendar |
| 7064: | "DURATION' properties MUST be present in the associated "VEVENT" |
| 7067: | the "DSTART" and "DURATION' properties MUST be present in the |
| 7082: | ; but MUST NOT occur more than once |
| 7104: | ; but MUST NOT occur more than once |
| 7184: | Conformance: This property MUST be included in the "VEVENT", "VTODO", |
| 7187: | Description: The value MUST be specified in the UTC time format. |
| 7237: | Description: The property value MUST be specified in the UTC time |
| 7277: | MUST be incremented: |
| 7297: | MUST increment the sequence number when ever it makes changes to |
| 7479: | ; but MUST NOT occur more than once |
| 7733: | any time, it MUST NOT be used to record busy time no matter what |
| 7891: | The property description MUST be posted to the new property |
| 7896: | Discussion on the new property MUST be allowed to take place on the |
| 7897: | list for a minimum of two weeks. Consensus MUST be reached on the |
| REQUIRED | |
| Line | Conditions |
| 387: | REQUIRED parameters: none |
| 1530: | ; participation is REQUIRED |
| 2805: | ; 'prodid' and 'version' are both REQUIRED, |
| 3324: | ; 'tzid' is REQUIRED, but MUST NOT occur more |
| 3370: | ; the following are each REQUIRED, |
| 3748: | ; 'action' and 'trigger' are both REQUIRED, |
| 3775: | ; the following are all REQUIRED, |
| 3806: | ; the following are all REQUIRED, |
| 3811: | ; the following is REQUIRED, |
| 3833: | ; the following are all REQUIRED, |
| 4212: | iCalendar specification that is REQUIRED in order to interpret the |
| 5195: | REQUIRED in "VEVENT" calendar components. Events can have a start |
| 5205: | property is REQUIRED within each STANDARD and DAYLIGHT part included |
| 7223: | ; the following is REQUIRED, |
| 8075: | is not backward compatible, but is not REQUIRED to do so. |
| 8314: | followed, or as REQUIRED to translate it into languages other than |
| SHOULD/SHOULD NOT | |
| Line | Condition |
| 400: | information contained within the body part. It SHOULD NOT be used to |
| 630: | Lines of text SHOULD NOT be longer than 75 octets, excluding the line |
| 631: | break. Long content lines SHOULD be split into a multiple line |
| 656: | a content line, lines longer than 75 octets SHOULD be folded |
| 685: | ; longer than 75 octets SHOULD be folded according to |
| 827: | Binary content information in an iCalendar object SHOULD be |
| 829: | content information SHOULD be placed in an external MIME entity that |
| 834: | [RFC 2045]. Inline binary contact SHOULD only be used in applications |
| 1933: | relative time zone information, SHOULD interpret the value as being |
| 1937: | event at different actual times. Floating time SHOULD only be used |
| 2607: | relative time zone information, SHOULD interpret the value as being |
| 2610: | different UTC times; floating time SHOULD only be used where that is |
| 3252: | "DTEND" properties SHOULD be specified prior to any "FREEBUSY" |
| 3523: | VTIMEZONE definition. TZURL SHOULD refer to a resource that is |
| 3525: | SHOULD NOT normally be a file: URL or other URL that is not widely- |
| 3979: | calendar component SHOULD be sent as attachments to the message. |
| 3990: | alarm capability, the PROCEDURE type of alarm SHOULD be treated by |
| 4063: | component. They SHOULD be specified after the "BEGIN:VCALENDAR" |
| 4174: | Description: The vendor of the implementation SHOULD assure that this |
| 4178: | This property SHOULD not be used to alter the interpretation of an |
| 5317: | SHOULD be sorted in ascending order, based on start time and then end |
| 5322: | "FREEBUSY" property values SHOULD all be of the same "FBTYPE" |
| 5392: | with the calendar SHOULD be recorded as OPAQUE, allowing them to be |
| 5394: | up the individual's (or resource's) time SHOULD be recorded as |
| 7858: | 1. Content lines longer than 75 octets SHOULD be folded. |
| 7870: | DATE-TIME), they SHOULD specify values in the same time format |
| 7881: | specified by "ATTENDEE" properties in the request, they SHOULD |
| 7882: | respond to only one of the requests. The calendar user SHOULD |
| 7901: | then a value of "00" SHOULD be specified for the seconds |
| 7905: | type, it SHOULD be treated as TEXT. |
| 7907: | 9. TZURL values SHOULD NOT be specified as a FILE URI type. This URI |
| MAY | |
| Line | Condition |
| 444: | This parameter MAY only specify semantics already specified by the |
| 2895: | ; and MAY occur more than once |
| 3029: | ; and MAY occur more than once |
| 3097: | ; and MAY occur more than once |
| 3193: | ; and MAY occur more than once |
| 3343: | ..; and each MAY occur more than once. |
| 3348: | ; and MAY occur more than once |
| 3376: | ; and MAY occur more than once |
| 3765: | ; and MAY occur more than once |
| 3796: | ; and MAY occur more than once |
| 3812: | ; and MAY occur more than once |
| 3823: | ; and MAY occur more than once |
| 3859: | ; and MAY occur more than once |
| 4310: | ; and MAY occur more than once |
| 4367: | ; and MAY occur more than once |
| 4460: | ; and MAY occur more than once |
| 4523: | ; and MAY occur more than once |
| 4569: | real number, respectively. The longitude and latitude values MAY be |
| 4572: | MUST accept values of this precision and MAY truncate values of |
| 4687: | ; and MAY occur more than once |
| 4867: | ; and MAY occur more than once |
| 5005: | ; and MAY occur more than once |
| 5094: | ; and MAY occur more than once |
| 5153: | ; and MAY occur more than once |
| 5230: | ; and MAY occur more than once |
| 5347: | ; and MAY occur more than once |
| 5525: | ; and MAY occur more than once |
| 5763: | ; and MAY occur more than once |
| 5864: | ; and MAY occur more than once |
| 5968: | ; and MAY occur more than once |
| 6077: | ; and MAY occur more than once |
| 6156: | ; and MAY occur more than once |
| 6364: | ; and MAY occur more than once |
| 6512: | ; and MAY occur more than once |
| 7216: | ; and MAY occur more than once |
| 7229: | ; and MAY occur more than once |
| 7618: | ; and MAY occur more than once |