Network Working Group B. Desruisseaux, Ed. Internet-Draft Oracle Expires: April 14, 2006 C. Stoner, Ed. IBM October 11, 2005 Internet Calendaring and Scheduling Core Object Specification (iCalendar) draft-ietf-calsify-rfc2445bis-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 14, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract Calendar systems export, transport and sometimes even store calendar information in a standard, interoperable format. This memo defines the common format for openly exchanging calendaring and scheduling information across the Internet, known as the iCalendar object format. An iCalendar object may represent an event, to-do or task, or journal entry (note). Desruisseaux & Stoner Expires April 14, 2006 [Page 1] Internet-Draft iCalendar October 2005 Comments are solicited and should be addressed to the working group's mailing list at ietf-calsify@osafoundation.org and/or the editor. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1. Related Memos . . . . . . . . . . . . . . . . . . . . . 5 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Document Conventions . . . . . . . . . . . . . . . . . . . . 8 3.1. Formatting Conventions . . . . . . . . . . . . . . . . . 8 4. International Considerations . . . . . . . . . . . . . . . . 10 5. General Syntax . . . . . . . . . . . . . . . . . . . . . . . 11 5.1. Character Set . . . . . . . . . . . . . . . . . . . . . 11 5.2. Case Sensitivity . . . . . . . . . . . . . . . . . . . . 11 5.3. Content Lines . . . . . . . . . . . . . . . . . . . . . 11 5.4. List and Field Separators . . . . . . . . . . . . . . . 14 5.5. Multiple Property Values . . . . . . . . . . . . . . . . 14 5.6. Binary Content . . . . . . . . . . . . . . . . . . . . . 15 5.7. Property Parameter Syntax . . . . . . . . . . . . . . . 15 6. iCalendar Objects . . . . . . . . . . . . . . . . . . . . . . 17 7. Calendar Components . . . . . . . . . . . . . . . . . . . . . 18 7.1. Event Component . . . . . . . . . . . . . . . . . . . . 19 7.2. To-do Component . . . . . . . . . . . . . . . . . . . . 22 7.3. Journal Component . . . . . . . . . . . . . . . . . . . 24 7.4. Free/Busy Component . . . . . . . . . . . . . . . . . . 26 7.5. Time Zone Component . . . . . . . . . . . . . . . . . . 29 7.6. Alarm Component . . . . . . . . . . . . . . . . . . . . 38 8. Properties . . . . . . . . . . . . . . . . . . . . . . . . . 45 8.1. Calendar Properties . . . . . . . . . . . . . . . . . . 45 8.1.1. Calendar Scale . . . . . . . . . . . . . . . . . . . 45 8.1.2. Method . . . . . . . . . . . . . . . . . . . . . . . 46 8.1.3. Product Identifier . . . . . . . . . . . . . . . . . 47 8.1.4. Version . . . . . . . . . . . . . . . . . . . . . . . 48 8.2. Descriptive Component Properties . . . . . . . . . . . . 49 8.2.1. Attachment . . . . . . . . . . . . . . . . . . . . . 49 8.2.2. Categories . . . . . . . . . . . . . . . . . . . . . 50 8.2.3. Classification . . . . . . . . . . . . . . . . . . . 51 8.2.4. Comment . . . . . . . . . . . . . . . . . . . . . . . 52 8.2.5. Description . . . . . . . . . . . . . . . . . . . . . 53 8.2.6. Geographic Position . . . . . . . . . . . . . . . . . 54 8.2.7. Location . . . . . . . . . . . . . . . . . . . . . . 56 8.2.8. Percent Complete . . . . . . . . . . . . . . . . . . 57 8.2.9. Priority . . . . . . . . . . . . . . . . . . . . . . 58 8.2.10. Resources . . . . . . . . . . . . . . . . . . . . . . 59 8.2.11. Free/Busy Time Type . . . . . . . . . . . . . . . . . 60 8.2.12. Participation Status . . . . . . . . . . . . . . . . 61 8.2.13. Status . . . . . . . . . . . . . . . . . . . . . . . 63 Desruisseaux & Stoner Expires April 14, 2006 [Page 2] Internet-Draft iCalendar October 2005 8.2.14. Summary . . . . . . . . . . . . . . . . . . . . . . . 64 8.2.15. Date and Time Component Properties . . . . . . . . . 65 8.2.16. Time Zone Component Properties . . . . . . . . . . . 73 8.2.17. Relationship Component Properties . . . . . . . . . . 77 8.2.18. Calendar User Type . . . . . . . . . . . . . . . . . 86 8.2.19. Directory Entry Reference . . . . . . . . . . . . . . 87 8.2.20. Recurrence ID . . . . . . . . . . . . . . . . . . . . 87 8.2.21. Related To . . . . . . . . . . . . . . . . . . . . . 89 8.2.22. Uniform Resource Locator . . . . . . . . . . . . . . 91 8.2.23. Unique Identifier . . . . . . . . . . . . . . . . . . 91 8.2.24. Relationship Type . . . . . . . . . . . . . . . . . . 93 8.3. Recurrence Component Properties . . . . . . . . . . . . 94 8.3.1. Exception Date/Times . . . . . . . . . . . . . . . . 94 8.3.2. Exception Rule . . . . . . . . . . . . . . . . . . . 95 8.3.3. Recurrence Date/Times . . . . . . . . . . . . . . . . 97 8.3.4. Recurrence Identifier Range . . . . . . . . . . . . . 98 8.3.5. Recurrence Rule . . . . . . . . . . . . . . . . . . . 99 8.4. Alarm Component Properties . . . . . . . . . . . . . . . 110 8.4.1. Action . . . . . . . . . . . . . . . . . . . . . . . 110 8.4.2. Alarm Repeat Count . . . . . . . . . . . . . . . . . 111 8.4.3. Alarm Trigger . . . . . . . . . . . . . . . . . . . . 111 8.5. Alarm Trigger Relationship . . . . . . . . . . . . . . . 114 8.6. Change Management Component Properties . . . . . . . . . 114 8.6.1. Date/Time Created . . . . . . . . . . . . . . . . . . 114 8.6.2. Date/Time Stamp . . . . . . . . . . . . . . . . . . . 115 8.6.3. Last Modified . . . . . . . . . . . . . . . . . . . . 116 8.6.4. Sequence Number . . . . . . . . . . . . . . . . . . . 117 8.7. Miscellaneous Component Properties . . . . . . . . . . . 118 8.7.1. RSVP Expectation . . . . . . . . . . . . . . . . . . 118 8.7.2. Language . . . . . . . . . . . . . . . . . . . . . . 119 8.7.3. Group or List Membership . . . . . . . . . . . . . . 120 8.7.4. Alternate Text Representation . . . . . . . . . . . . 121 8.7.5. Inline Encoding . . . . . . . . . . . . . . . . . . . 121 8.7.6. Format Type . . . . . . . . . . . . . . . . . . . . . 122 8.7.7. Non-standard Properties . . . . . . . . . . . . . . . 123 8.7.8. Request Status . . . . . . . . . . . . . . . . . . . 124 9. iCalendar Object Examples . . . . . . . . . . . . . . . . . . 127 10. Recommended Practices . . . . . . . . . . . . . . . . . . . . 132 11. Registration of Content Type Elements . . . . . . . . . . . . 134 11.1. Registration of New and Modified iCalendar Object Methods . . . . . . . . . . . . . . . . . . . . . . . . 134 11.2. Registration of New Properties . . . . . . . . . . . . . 134 11.3. Define the property . . . . . . . . . . . . . . . . . . 134 11.4. Post the Property definition . . . . . . . . . . . . . . 136 11.5. Allow a comment period . . . . . . . . . . . . . . . . . 136 11.6. Submit the property for approval . . . . . . . . . . . . 136 11.7. Property Change Control . . . . . . . . . . . . . . . . 136 12. Property Parameters . . . . . . . . . . . . . . . . . . . . . 138 Desruisseaux & Stoner Expires April 14, 2006 [Page 3] Internet-Draft iCalendar October 2005 13. Value Data Types . . . . . . . . . . . . . . . . . . . . . . 139 13.1. Binary . . . . . . . . . . . . . . . . . . . . . . . . . 139 13.2. Boolean . . . . . . . . . . . . . . . . . . . . . . . . 140 13.3. Calendar User Address . . . . . . . . . . . . . . . . . 140 13.4. Date . . . . . . . . . . . . . . . . . . . . . . . . . . 141 13.5. Date-Time . . . . . . . . . . . . . . . . . . . . . . . 141 13.6. Duration . . . . . . . . . . . . . . . . . . . . . . . . 143 13.7. Period of Time . . . . . . . . . . . . . . . . . . . . . 144 13.8. Time Zone Identifier . . . . . . . . . . . . . . . . . . 145 13.9. Recurrence Rule . . . . . . . . . . . . . . . . . . . . 146 13.10. Float . . . . . . . . . . . . . . . . . . . . . . . . . 152 13.11. Integer . . . . . . . . . . . . . . . . . . . . . . . . 152 13.12. Text . . . . . . . . . . . . . . . . . . . . . . . . . . 153 13.13. Time . . . . . . . . . . . . . . . . . . . . . . . . . . 154 13.14. URI . . . . . . . . . . . . . . . . . . . . . . . . . . 156 13.15. UTC Offset . . . . . . . . . . . . . . . . . . . . . . . 157 14. Security Considerations . . . . . . . . . . . . . . . . . . . 159 15. IANA MIME Media Type Registration . . . . . . . . . . . . . . 160 16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 163 17. Normative References . . . . . . . . . . . . . . . . . . . . 163 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 165 Intellectual Property and Copyright Statements . . . . . . . . . 166 Desruisseaux & Stoner Expires April 14, 2006 [Page 4] Internet-Draft iCalendar October 2005 1. Introduction 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. However, the longer term growth of calendaring and scheduling, is currently limited by the lack of Internet standards for the message content types that are central to these knowledgeware applications. This memo is intended to progress the level of interoperability possible between dissimilar calendaring and scheduling applications. This memo defines a MIME [5] 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 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. [[Comment.1: Removed forward reference to ITIP (unnecessary) --Lisa D]] The memo also includes a formal grammar for the content type based on the Internet ABNF defined in RFC 2234 [8]. 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. 1.1. Related Memos 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, [ICAL], specifies a core specification of objects, data types, properties and property Desruisseaux & Stoner Expires April 14, 2006 [Page 5] Internet-Draft iCalendar October 2005 parameters. [ITIP] - specifies an interoperability protocol for scheduling between different implementations; [IMIP] specifies an Internet email binding for [ITIP]. 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. [[Comment.2: If we keep this section on related memos, we have to think about whether ITIP and IMIP are progressing to Draft at the same time, whether to update those references and whether to add CalDAV or other references. --Lisa D]] Desruisseaux & Stoner Expires April 14, 2006 [Page 6] Internet-Draft iCalendar October 2005 2. Overview This draft section provides a high-level overview of the concepts of iCalendar and the organization of this document. An iCalendar object contains a set of calendar properties and a set of components. Components consist of a set of component properties. Properties consist of a property name, a set of parameters, and a property value. The preliminary material of this document includes the introduction, this overview, some document conventions and the considerations for internationalization. Section 5 provides the general syntax rules used by all of iCalendar, such as character set, line length and line break rules, and which characters are separators. Section 6 defines the iCalendar object itself, and Section 7 covers the components that appear in iCalendar objects. Desruisseaux & Stoner Expires April 14, 2006 [Page 7] Internet-Draft iCalendar October 2005 3. Document Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY" and "OPTIONAL" in this document are to be interoperated as described in RFC 2119 [7]. 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 RFC 2234 [8]. Readers intending on implementing this format defined in this memo should be familiar with this notation in order to properly interpret the specifications of this memo. 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. [[Comment.3: This section can be deleted because it provides practically no information and is not a normative reference: The format for the iCalendar object is based on the syntax of the RFC 2425 content type. While the iCalendar object is not a profile of the RFC 2425 content type, it does reuse a number of the elements from the RFC 2425 specification. --Lisa D]] 3.1. Formatting Conventions The mechanisms 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 [ITIP] 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 [ITIP]. 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 8] Internet-Draft iCalendar October 2005 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 data 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" data type to specify repeating components based on an interval of one minute or more. Desruisseaux & Stoner Expires April 14, 2006 [Page 9] Internet-Draft iCalendar October 2005 4. International Considerations In the rest of 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 or US-ASCII compatible sets (for example the ISO-8859-x family, UTF- 8, ISO-2022-xx, KOI8-R). If a non-US-ASCII compatible character set is used, appropriate code-point from that character set MUST be chosen instead. Use of non-US-ASCII-compatible character sets is NOT recommended. Desruisseaux & Stoner Expires April 14, 2006 [Page 10] Internet-Draft iCalendar October 2005 5. General Syntax 5.1. Character Set The default character set for an iCalendar object is UTF-8 as defined in RFC 2279 [9]. The "charset" Content-Type parameter can be used in MIME transports to specify any other IANA registered character set. [[Comment.4: I think we need to say something about interoperability problems which result from using any other charset. --Lisa D]] 5.2. Case Sensitivity 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. 5.3. Content Lines 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 the 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: DESCRIPTION:This is a long description that exists on a long line. Figure 1 Can be represented as: DESCRIPTION:This is a lo ng description that exists on a long line. Figure 2 Desruisseaux & Stoner Expires April 14, 2006 [Page 11] Internet-Draft iCalendar October 2005 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. When generating a content line, lines longer than 75 octets SHOULD be folded according to the folding procedure described above. Content lines are CRLF-separated. [[Comment.5: Removed reference to 2425 again and simply stated that lines are CRLF-separated --Lisa]] The following ABNF defines the lines of content in an iCalendar object: contentline = name *(";" param ) ":" value CRLF ; This ABNF is just a general definition for an initial parsing ; of the content line into its property name, parameter list, ; and value string ; When parsing a content line, folded lines MUST first ; be unfolded according to the unfolding procedure ; described above. When generating a content line, lines ; longer than 75 octets SHOULD be folded according to ; the folding procedure described above. name = x-name / iana-token iana-token = 1*(ALPHA / DIGIT / "-") ; iCalendar identifier registered with IANA x-name = "X-" [vendorid "-"] 1*(ALPHA / DIGIT / "-") ; Reservered for experimental use. Not intended for use in ; released products. vendorid = 3*(ALPHA / DIGIT) ;Vendor identification param = param-name "=" param-value *("," param-value) ; Each property defines the specific ABNF for the parameters ; allowed on the property. Refer to specific properties for ; precise parameter ABNF. param-name = iana-token / x-token param-value = paramtext / quoted-string paramtext = *SAFE-CHAR Desruisseaux & Stoner Expires April 14, 2006 [Page 12] Internet-Draft iCalendar October 2005 value = *VALUE-CHAR quoted-string = DQUOTE *QSAFE-CHAR DQUOTE NON-US-ASCII = %x80-F8 ; Use restricted by charset parameter ; on outer MIME object (UTF-8 preferred) QSAFE-CHAR = WSP / %x21 / %x23-7E / NON-US-ASCII ; Any character except CTLs and DQUOTE SAFE-CHAR = WSP / %x21 / %x23-2B / %x2D-39 / %x3C-7E / NON-US-ASCII ; Any character except CTLs, DQUOTE, ";", ":", "," VALUE-CHAR = WSP / %x21-7E / NON-US-ASCII ; Any textual character CR = %x0D ; carriage return LF = %x0A ; line feed CRLF = CR LF ; Internet standard newline CTL = %x00-08 / %x0A-1F / %x7F ; Controls ALPHA = %x41-5A / %x61-7A ; A-Z / a-z DIGIT = %x30-39 ; 0-9 DQUOTE = %x22 ; Quotation Mark WSP = SPACE / HTAB SPACE = %x20 HTAB = %x09 Figure 3 The property value component of a content line has a format that is property specific. Refer to the section describing each property for Desruisseaux & Stoner Expires April 14, 2006 [Page 13] Internet-Draft iCalendar October 2005 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. 5.4. List and Field Separators 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, a SEMICOLON or a COMMA character 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. ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:MAILTO: jsmith@host.com RDATE;VALUE=DATE:19970304,19970504,19970704,19970904 5.5. Multiple Property Values 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 14] Internet-Draft iCalendar October 2005 5.6. Binary Content 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 [RFC 2045]. Inline binary contact 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: ATTACH:http://xyz.com/public/quarterly-report.doc The following example specifies an "ATTACH" property with inline binary encoded content information: ATTACH;FMTTYPE=image/basic;ENCODING=BASE64;VALUE=BINARY: MIICajCCAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQAwdzELMAkGA1U EBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb25zIE [...remainder of "BASE64" encoded binary data...] 5.7. Property Parameter Syntax 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 data 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 DOUBLE-QUOTE (US-ASCII decimal 22) character. The DOUBLE-QUOTE (US-ASCII decimal 22) character is used as a delimiter for parameter values that contain restricted characters or URI text. For example: DESCRIPTION;ALTREP="http://www.wiz.org":The Fall'98 Wild Wizards Desruisseaux & Stoner Expires April 14, 2006 [Page 15] Internet-Draft iCalendar October 2005 Conference - - Las Vegas, NV, USA Property parameter values that are not in quoted strings are case insensitive. Desruisseaux & Stoner Expires April 14, 2006 [Page 16] Internet-Draft iCalendar October 2005 6. iCalendar Objects The Calendaring and Scheduling Core Object is a collection of calendaring and scheduling information. Typically, this information will consist of a single iCalendar object. However, multiple iCalendar objects can be sequentially grouped together. The first line and last line of the iCalendar object MUST contain a pair of iCalendar object delimiter strings. The syntax for an iCalendar object is as follows: icalobject = 1*("BEGIN" ":" "VCALENDAR" CRLF icalbody "END" ":" "VCALENDAR" CRLF) Figure 8 The following is a simple example of an iCalendar object: BEGIN:VCALENDAR VERSION:2.0 PRODID:-//hacksw/handcal//NONSGML v1.0//EN BEGIN:VEVENT DTSTART:19970714T170000Z DTEND:19970715T035959Z SUMMARY:Bastille Day Party END:VEVENT END:VCALENDAR Figure 9 Desruisseaux & Stoner Expires April 14, 2006 [Page 17] Internet-Draft iCalendar October 2005 7. Calendar Components The body of an 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 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, or free/busy time information, or an alarm. The body of the iCalendar object is defined by the following notation: icalbody = calprops component calprops = 2*( ; 'prodid' and 'version' are both REQUIRED, ; but MUST NOT occur more than once prodid /version / ; 'calscale' and 'method' are optional, ; but MUST NOT occur more than once calscale / method / x-prop ) component = 1*(eventc / todoc / journalc / freebusyc / / timezonec / iana-comp / x-comp) iana-comp = "BEGIN" ":" iana-token CRLF 1*contentline "END" ":" iana-token CRLF x-comp = "BEGIN" ":" x-name CRLF 1*contentline "END" ":" x-name CRLF Desruisseaux & Stoner Expires April 14, 2006 [Page 18] Internet-Draft iCalendar October 2005 Figure 10 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 is possible that is used to capture a complete snapshot of the contents of a calendar (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. 7.1. Event Component Component Name: VEVENT Purpose: Provide a grouping of component properties that describe an event. Desruisseaux & Stoner Expires April 14, 2006 [Page 19] Internet-Draft iCalendar October 2005 Formal Definition: A "VEVENT" calendar component is defined by the following notation: eventc = "BEGIN" ":" "VEVENT" CRLF eventprop *alarmc "END" ":" "VEVENT" CRLF eventprop = *( ; the following are optional, ; but MUST NOT occur more than once class / created / description / dtstart / geo / last-mod / location / organizer / priority / dtstamp / seq / status / summary / transp / uid / url / recurid / ; either 'dtend' or 'duration' may appear in ; a 'eventprop', but 'dtend' and 'duration' ; MUST NOT occur in the same 'eventprop' dtend / duration / ; the following are optional, ; and MAY occur more than once attach / attendee / categories / comment / contact / exdate / exrule / rstatus / related / resources / rdate / rrule / x-prop ) Figure 11 Description: 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 20] Internet-Draft iCalendar October 2005 DATE value type for the "DTSTART" property instead of the default data 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). 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 data type but no "DTEND" property, the events non-inclusive end is the end of the calendar date specified by the "DTSTART" property. For cases where a "VEVENT" calendar component specifies a "DTSTART" property with a DATE-TIME data 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. Example 1: 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: BEGIN:VEVENT UID:19970901T130000Z-123401@host.com DTSTAMP:19970901T1300Z DTSTART:19970903T163000Z DTEND:19970903T190000Z SUMMARY:Annual Employee Review CLASS:PRIVATE CATEGORIES:BUSINESS,HUMAN RESOURCES END:VEVENT Figure 12 Desruisseaux & Stoner Expires April 14, 2006 [Page 21] Internet-Draft iCalendar October 2005 Example 2: 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: BEGIN:VEVENT UID:19970901T130000Z-123402@host.com DTSTAMP:19970901T1300Z DTSTART:19970401T163000Z DTEND:19970402T010000Z SUMMARY:Laurel is in sensitivity awareness class. CLASS:PUBLIC CATEGORIES:BUSINESS,HUMAN RESOURCES TRANSP:TRANSPARENT END:VEVENT Figure 13 Example 3: The following is an example of the "VEVENT" calendar component used to represent an anniversary that will occur annually. Since it takes up no time, it will not appear as opaque in a search for busy time; no matter what the value of the "TRANSP" property indicates: BEGIN:VEVENT UID:19970901T130000Z-123403@host.com DTSTAMP:19970901T1300Z DTSTART:19971102 SUMMARY:Our Blissful Anniversary CLASS:CONFIDENTIAL CATEGORIES:ANNIVERSARY,PERSONAL,SPECIAL OCCASION RRULE:FREQ=YEARLY END:VEVENT Figure 14 7.2. To-do Component Component Name: VTODO Purpose: Provide a grouping of calendar properties that describe a to-do. Desruisseaux & Stoner Expires April 14, 2006 [Page 22] Internet-Draft iCalendar October 2005 Formal Definition: A "VTODO" calendar component is defined by the following notation: todoc = "BEGIN" ":" "VTODO" CRLF todoprop *alarmc "END" ":" "VTODO" CRLF todoprop = *( ; the following are optional, ; but MUST NOT occur more than once class / completed / created / description / dtstamp / dtstart / geo / last-mod / location / organizer / percent / priority / recurid / seq / status / summary / uid / url / ; either 'due' or 'duration' may appear in ; a 'todoprop', but 'due' and 'duration' ; MUST NOT occur in the same 'todoprop' due / duration / ; the following are optional, ; and MAY occur more than once attach / attendee / categories / comment / contact / exdate / exrule / rstatus / related / resources / rdate / rrule / x-prop ) Figure 15 Description: 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 "VTODO" 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 23] Internet-Draft iCalendar October 2005 Example: The following is an example of a "VTODO" calendar component: BEGIN:VTODO UID:19970901T130000Z-123404@host.com DTSTAMP:19970901T1300Z DTSTART:19970415T133000Z DUE:19970416T045959Z SUMMARY:1996 Income Tax Preparation CLASS:CONFIDENTIAL CATEGORIES:FAMILY,FINANCE PRIORITY:1 STATUS:NEEDS-ACTION END:VTODO Figure 16 7.3. Journal Component Component Name: VJOURNAL Purpose: Provide a grouping of component properties that describe a journal entry. Desruisseaux & Stoner Expires April 14, 2006 [Page 24] Internet-Draft iCalendar October 2005 Formal Definition: A "VJOURNAL" calendar component is defined by the following notation: journalc = "BEGIN" ":" "VJOURNAL" CRLF jourprop "END" ":" "VJOURNAL" CRLF jourprop = *( ; the following are optional, ; but MUST NOT occur more than once class / created / description / dtstart / dtstamp / last-mod / organizer / recurid / seq / status / summary / uid / url / ; the following are optional, ; and MAY occur more than once attach / attendee / categories / comment / contact / exdate / exrule / related / rdate / rrule / rstatus / x-prop ) Figure 17 Description: 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 25] Internet-Draft iCalendar October 2005 component, with the "RELATED-TO" property. Example: The following is an example of the "VJOURNAL" calendar component: BEGIN:VJOURNAL UID:19970901T130000Z-123405@host.com DTSTAMP:19970901T1300Z DTSTART;VALUE=DATE:19970317 SUMMARY:Staff meeting minutes DESCRIPTION:1. Staff meeting: Participants include Joe\, Lisa and Bob. Aurora project plans were reviewed. There is currently no budget reserves for this project. Lisa will escalate to management. Next meeting on Tuesday.\n 2. Telephone Conference: ABC Corp. sales representative called to discuss new printer. Promised to get us a demo by Friday.\n 3. Henry Miller (Handsoff Insurance): Car was totaled by tree. Is looking into a loaner car. 654-2323 (tel). END:VJOURNAL Figure 18 7.4. Free/Busy Component Component Name: VFREEBUSY Purpose: 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 26] Internet-Draft iCalendar October 2005 Formal Definition: A "VFREEBUSY" calendar component is defined by the following notation: freebusyc = "BEGIN" ":" "VFREEBUSY" CRLF fbprop "END" ":" "VFREEBUSY" CRLF fbprop = *( ; the following are optional, ; but MUST NOT occur more than once contact / dtstart / dtend / duration / dtstamp / organizer / uid / url / ; the following are optional, ; and MAY occur more than once attendee / comment / freebusy / rstatus / x-prop ) Figure 19 Description: 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 27] Internet-Draft iCalendar October 2005 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. In a free time request, these properties can be used in combination with the "DURATION" property to represent a request for a duration of free time within a specified window of time. The recurrence properties ("RRULE", "EXRULE", "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. Example 1: The following is an example of a "VFREEBUSY" calendar component used to request free or busy time information: BEGIN:VFREEBUSY ORGANIZER:MAILTO:jane_doe@host1.com ATTENDEE:MAILTO:john_public@host2.com DTSTART:19971015T050000Z DTEND:19971016T050000Z DTSTAMP:19970901T083000Z END:VFREEBUSY Figure 20 Desruisseaux & Stoner Expires April 14, 2006 [Page 28] Internet-Draft iCalendar October 2005 Example 2: A "VFREEBUSY" calendar component used to reply to the request with busy time information. BEGIN:VFREEBUSY ORGANIZER:MAILTO:jane_doe@host1.com ATTENDEE:MAILTO:john_public@host2.com DTSTAMP:19970901T100000Z FREEBUSY;VALUE=PERIOD:19971015T050000Z/PT8H30M, 19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M URL:http://host2.com/pub/busy/jpublic-01.ifb COMMENT:This iCalendar file contains busy time information for the next three months. END:VFREEBUSY Figure 21 Example 3: a "VFREEBUSY" calendar component used to publish busy time information. BEGIN:VFREEBUSY ORGANIZER:jsmith@host.com DTSTART:19980313T141711Z DTEND:19980410T141711Z FREEBUSY:19980314T233000Z/19980315T003000Z FREEBUSY:19980316T153000Z/19980316T163000Z FREEBUSY:19980318T030000Z/19980318T040000Z URL:http://www.host.com/calendar/busytime/jsmith.ifb END:VFREEBUSY Figure 22 7.5. Time Zone Component Component Name: VTIMEZONE Purpose: Provide a grouping of component properties that defines a time zone. Formal Definition: A "VTIMEZONE" calendar component is defined by the following notation: timezonec = "BEGIN" ":" "VTIMEZONE" CRLF 2*( ; 'tzid' is required, but MUST NOT occur more ; than once Desruisseaux & Stoner Expires April 14, 2006 [Page 29] Internet-Draft iCalendar October 2005 tzid / ; 'last-mod' and 'tzurl' are optional, but MUST NOT occur more than once last-mod / tzurl / ; one of 'standardc' or 'daylightc' MUST occur ..; and each MAY occur more than once. standardc / daylightc / ; the following is optional, ; and MAY occur more than once x-prop ) "END" ":" "VTIMEZONE" CRLF standardc = "BEGIN" ":" "STANDARD" CRLF tzprop "END" ":" "STANDARD" CRLF daylightc = "BEGIN" ":" "DAYLIGHT" CRLF tzprop "END" ":" "DAYLIGHT" CRLF tzprop = 3*( ; the following are each REQUIRED, ; but MUST NOT occur more than once dtstart / tzoffsetto / tzoffsetfrom / ; the following are optional, ; and MAY occur more than once comment / rdate / rrule / tzname / x-prop ) Desruisseaux & Stoner Expires April 14, 2006 [Page 30] Internet-Draft iCalendar October 2005 Figure 23 Description: 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 Rule +-----------+-------------------------+--------+--------------+ | Date | (Date/Time) | Offset | Abbreviation | +-----------+-------------------------+--------+--------------+ | 1967-* | last Sun in Oct, 02:00 | -0500 | EST | | | | | | | 1967-1973 | last Sun in Apr, 02:00 | -0400 | EDT | | | | | | | 1974-1974 | Jan 6, 02:00 | -0400 | EDT | | | | | | | 1975-1975 | Feb 23, 02:00 | -0400 | EDT | | | | | | | 1976-1986 | last Sun in Apr, 02:00 | -0400 | EDT | | | | | | | 1987-* | first Sun in Apr, 02:00 | -0400 | EDT | +-----------+-------------------------+--------+--------------+ 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 Olson time zone database [TZ] 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 31] Internet-Draft iCalendar October 2005 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 be present if the iCalendar object contains an RRULE that generates dates on both sides of a time zone shift (e.g. both in Standard Time and Daylight Saving Time) unless the iCalendar object intends to convey a floating time (See Section 13.13 for proper interpretation of floating time). It can be present if the iCalendar object does not contain such a RRULE. In addition, if a RRULE is present, there MUST be valid time zone information for all recurrence instances. The "VTIMEZONE" calendar component MUST include the "TZID" property and at least one definition of a standard or daylight component. The standard or daylight component 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. 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 32] Internet-Draft iCalendar October 2005 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 VTIMZONE 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 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 local DATE-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: DTSTART:19671029T020000 TZOFFSETFROM:-0400 Figure 24 Desruisseaux & Stoner Expires April 14, 2006 [Page 33] Internet-Draft iCalendar October 2005 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. It may be specified multiple times, to allow for specifying multiple language variants of the time zone names. This could be used for displaying dates. If specified, the onset for the observance defined by the time zone sub-component is defined by either the "RRULE" or "RDATE" property. If neither is specified, only one sub-component can be specified in the "VTIMEZONE" calendar component and it is assumed that the single observance specified is always in effect. 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 "TZOFFSETTO" properties MUST be used when generating the onset date-time values (instances) from the RRULE. Alternatively, the "RDATE" property can 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 local DATE-TIME value in UTC time. The optional "COMMENT" property is also allowed for descriptive explanatory text. Example: The following are examples of the "VTIMEZONE" calendar component: Desruisseaux & Stoner Expires April 14, 2006 [Page 34] Internet-Draft iCalendar October 2005 Example 1: Time zone information for the Eastern United States using "RDATE" property. Note that this is only suitable for a recurring event that starts on or later than April 6, 1997 at 03:00:00 EDT (i.e., the earliest effective transition date and time) and ends no later than April 7, 1998 02:00:00 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, 8am-9:00 AM, starting June 1, 1997, ending December 31, 1997. BEGIN:VTIMEZONE TZID:US-Eastern LAST-MODIFIED:19870101T000000Z BEGIN:STANDARD DTSTART:19971026T020000 RDATE:19971026T020000 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 TZNAME:EST END:STANDARD BEGIN:DAYLIGHT DTSTART:19970406T020000 RDATE:19970406T020000 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT END:VTIMEZONE Figure 25 Desruisseaux & Stoner Expires April 14, 2006 [Page 35] Internet-Draft iCalendar October 2005 Example 2: Current time zone rules for the Eastern United States 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. BEGIN:VTIMEZONE TZID:US-Eastern LAST-MODIFIED:19870101T000000Z TZURL:http://zones.stds_r_us.net/tz/US-Eastern BEGIN:STANDARD DTSTART:19671029T020000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 TZNAME:EST END:STANDARD BEGIN:DAYLIGHT DTSTART:19870405T020000 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT END:VTIMEZONE Figure 26 Desruisseaux & Stoner Expires April 14, 2006 [Page 36] Internet-Draft iCalendar October 2005 Example 3: A fictitious set of rules for the Eastern United States, where the Daylight Time rule has an effective end date (i.e., after that date, Daylight Time is no longer observed). BEGIN:VTIMEZONE TZID:US- -Fictitious-Eastern LAST-MODIFIED:19870101T000000Z BEGIN:STANDARD DTSTART:19671029T020000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 TZNAME:EST END:STANDARD BEGIN:DAYLIGHT DTSTART:19870405T020000 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT END:VTIMEZONE Figure 27 Desruisseaux & Stoner Expires April 14, 2006 [Page 37] Internet-Draft iCalendar October 2005 Example 4: A fictitious set of rules for the Eastern United States, 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. BEGIN:VTIMEZONE TZID:US- -Fictitious-Eastern LAST-MODIFIED:19870101T000000Z BEGIN:STANDARD DTSTART:19671029T020000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 TZNAME:EST END:STANDARD BEGIN:DAYLIGHT DTSTART:19870405T020000 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT BEGIN:DAYLIGHT DTSTART:19990424T020000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=4 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT END:VTIMEZONE Figure 28 7.6. Alarm Component Component Name: VALARM Purpose: Provide a grouping of component properties that define an alarm. Formal Definition: A "VALARM" calendar component is defined by the following notation: alarmc = "BEGIN" ":" "VALARM" CRLF (audioprop / dispprop / emailprop / procprop) "END" ":" "VALARM" CRLF audioprop = 2*( Desruisseaux & Stoner Expires April 14, 2006 [Page 38] Internet-Draft iCalendar October 2005 ; 'action' and 'trigger' are both REQUIRED, ; but MUST NOT occur more than once action / trigger / ; 'duration' and 'repeat' are both optional, ; and MUST NOT occur more than once each, ; but if one occurs, so MUST the other duration / repeat / ; the following is optional, ; but MUST NOT occur more than once attach / ; the following is optional, ; and MAY occur more than once x-prop ) dispprop = 3*( ; the following are all REQUIRED, ; but MUST NOT occur more than once action / description / trigger / ; 'duration' and 'repeat' are both optional, ; and MUST NOT occur more than once each, ; but if one occurs, so MUST the other duration / repeat / ; the following is optional, ; and MAY occur more than once *x-prop ) Desruisseaux & Stoner Expires April 14, 2006 [Page 39] Internet-Draft iCalendar October 2005 emailprop = 5*( ; the following are all REQUIRED, ; but MUST NOT occur more than once action / description / trigger / summary ; the following is REQUIRED, ; and MAY occur more than once attendee / ; 'duration' and 'repeat' are both optional, ; and MUST NOT occur more than once each, ; but if one occurs, so MUST the other duration / repeat / ; the following are optional, ; and MAY occur more than once attach / x-prop ) procprop = 3*( ; the following are all REQUIRED, ; but MUST NOT occur more than once action / attach / trigger / ; 'duration' and 'repeat' are both optional, ; and MUST NOT occur more than once each, ; but if one occurs, so MUST the other duration / repeat / ; 'description' is optional, ; and MUST NOT occur more than once description / ; the following is optional, ; and MAY occur more than once Desruisseaux & Stoner Expires April 14, 2006 [Page 40] Internet-Draft iCalendar October 2005 x-prop ) Figure 29 Description: 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. When the action is "PROCEDURE", the alarm MUST include one and only one "ATTACH" property, which MUST point to a procedure resource, which is invoked when the alarm is triggered. 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 41] Internet-Draft iCalendar October 2005 date and time of day value. 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 triggered. This repitition 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; EMAIL specifies an alarm that causes an electronic email message to be delivered to one or more email addresses; and PROCEDURE specifies an alarm that causes a procedure to be executed. The "ACTION" property MUST specify one and only one of these values. 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 42] Internet-Draft iCalendar October 2005 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. In a PROCEDURE alarm, the "ATTACH" property in the "VALARM" calendar component MUST specify a procedure or program that is intended to be invoked as the alarm effect. If the procedure or program is in a format that cannot be rendered, then no procedure alarm will be invoked. If the "DESCRIPTION" property is present, its value specifies the argument string to be passed to the procedure or program. "Calendar User Agents" that receive an iCalendar object with this category of alarm, can disable or allow the "Calendar User" to disable, or otherwise ignore this type of alarm. While a very useful alarm capability, the PROCEDURE type of alarm SHOULD be treated by the "Calendar User Agent" as a potential security risk. Example 1: 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. BEGIN:VALARM TRIGGER;VALUE=DATE-TIME:19970317T133000Z REPEAT:4 DURATION:PT15M ACTION:AUDIO ATTACH;FMTTYPE=audio/basic:ftp://host.com/pub/sounds/bell-01.aud END:VALARM Figure 30 Example 2: A "VALARM" calendar component that specifies a display alarm that will trigger 30 minutes before the scheduled start of the event or the due date/time of the to-do it is associated with and will repeat 2 more times at 15 minute intervals: BEGIN:VALARM TRIGGER:-PT30M REPEAT:2 DURATION:PT15M ACTION:DISPLAY DESCRIPTION:Breakfast meeting with executive\n team at 8:30 AM EST. END:VALARM Desruisseaux & Stoner Expires April 14, 2006 [Page 43] Internet-Draft iCalendar October 2005 Figure 31 Example 3: 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. BEGIN:VALARM TRIGGER:-P2D ACTION:EMAIL ATTENDEE:MAILTO:john_doe@host.com SUMMARY:*** REMINDER: SEND AGENDA FOR WEEKLY STAFF MEETING *** DESCRIPTION:A draft agenda needs to be sent out to the attendees to the weekly managers meeting (MGR-LIST). Attached is a pointer the document template for the agenda file. ATTACH;FMTTYPE=application/msword:http://host.com/templates/agen da.doc END:VALARM Figure 32 Example 4: A "VALARM" calendar component that specifies a procedural alarm that will trigger at a precise date/time and will repeat 23 more times at one hour intervals. The alarm will invoke a procedure file. BEGIN:VALARM TRIGGER;VALUE=DATE-TIME:19980101T050000Z REPEAT:23 DURATION:PT1H ACTION:PROCEDURE ATTACH;FMTTYPE=application/octet-stream:ftp://host.com/novo- procs/felizano.exe END:VALARM Figure 33 Desruisseaux & Stoner Expires April 14, 2006 [Page 44] Internet-Draft iCalendar October 2005 8. Properties A property is the definition of an individual attribute describing a calendar or a calendar component. A property takes the form defined by the "contentline" notation defined in section 4.1.1. The following is an example of a property: DTSTART:19960415T133000Z 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=US-Eastern:19980714T120000 is the same as DtStart;TzID=US-Eastern:19980714T120000. 8.1. Calendar Properties 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" property and prior to any calendar component. 8.1.1. Calendar Scale Property Name: CALSCALE Purpose: This property defines the calendar scale used for the calendar information specified in the iCalendar object. Value Type: TEXT do Property Parameters: Non-standard property parameters can be specified on this property. Conformance: Property can be specified in an iCalendar object. The default value is "GREGORIAN". Description: 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 45] Internet-Draft iCalendar October 2005 Formal Definition: The property is defined by the following notation: calscale = "CALSCALE" calparam ":" calvalue CRLF calparam = *(";" xparam) calvalue = "GREGORIAN" / iana-token Figure 35 Example: The following is an example of this property: CALSCALE:GREGORIAN Figure 36 8.1.2. Method Property Name: METHOD Purpose: This property defines the iCalendar object method associated with the calendar object. Value Type: TEXT Property Parameters: Non-standard property parameters can be specified on this property. Conformance: The property can be specified in an iCalendar object. Description: When used in a MIME message entity, the value of this property MUST be the same as the Content-Type "method" parameter value. This property can only appear once within the iCalendar object. 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 [ITIP]. 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 46] Internet-Draft iCalendar October 2005 Formal Definition: The property is defined by the following notation: method = "METHOD" metparam ":" metvalue CRLF metparam = *(";" xparam) metvalue = iana-token Example: The following is a hypothetical example of this property to convey that the iCalendar object is a request for a meeting: METHOD:REQUEST Figure 38 8.1.3. Product Identifier Property Name: PRODID Purpose: This property specifies the identifier for the product that created the iCalendar object. Value Type: TEXT Property Parameters: Non-standard property parameters can be specified on this property. Conformance: The property MUST be specified once in an iCalendar object. Description: 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 [ISO 9070]. 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 47] Internet-Draft iCalendar October 2005 Formal Definition: The property is defined by the following notation: prodid = "PRODID" pidparam ":" pidvalue CRLF pidparam = *(";" xparam) pidvalue = text ;Any text that describes the product and version ;and that is generally assured of being unique. Figure 39 Example: The following is an example of this property. It does not imply that English is the default language. PRODID:-//ABC Corporation//NONSGML My Product//EN Figure 40 8.1.4. Version Property Name: VERSION Purpose: 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. Value Type: TEXT Property Parameters: Non-standard property parameters can be specified on this property. Conformance: This property MUST be specified by an iCalendar object, but MUST only be specified once. Description: A value of "2.0" corresponds to this memo. Desruisseaux & Stoner Expires April 14, 2006 [Page 48] Internet-Draft iCalendar October 2005 Formal Definition: The property is defined by the following notation: version = "VERSION" verparam ":" vervalue CRLF verparam = *(";" xparam) vervalue = "2.0" ;This memo / maxver / (minver ";" maxver) minver = [A IANA registered iCalendar version identifier] ;Minimum iCalendar version needed to parse the iCalendar object maxver = [A IANA registered iCalendar version identifier] ;Maximum iCalendar version needed to parse the iCalendar object Example: The following is an example of this property: VERSION:2.0 8.2. Descriptive Component Properties The following properties can appear within calendar components, as specified by each component property definition. These specify descriptive information about calendar components. 8.2.1. Attachment Property Name: ATTACH Purpose: The property provides the capability to associate a document object with a calendar component. Value Type: 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. Property Parameters: Non-standard, inline encoding, format type and value data type property parameters can be specified on this property. Conformance: The property can be specified in a "VEVENT", "VTODO", "VJOURNAL" or "VALARM" calendar components. Description: The property can be specified within "VEVENT", "VTODO", "VJOURNAL", or "VALARM" calendar components. This property can be specified multiple times within an iCalendar object. Desruisseaux & Stoner Expires April 14, 2006 [Page 49] Internet-Draft iCalendar October 2005 Format Definition: The property is defined by the following notation: attach = "ATTACH" attparam ":" uri CRLF attach =/ "ATTACH" attparam ";" "ENCODING" "=" "BASE64" ";" "VALUE" "=" "BINARY" ":" binary attparam = *( ; the following is optional, ; but MUST NOT occur more than once (";" fmttypeparam) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) Example: The following are examples of this property: ATTACH:CID:jsmith.part3.960817T083000.xyzMail@host1.com ATTACH;FMTTYPE=application/postscript:ftp://xyzCorp.com/pub/ reports/r-960812.ps 8.2.2. Categories Property Name: CATEGORIES Purpose: This property defines the categories for a calendar component. Value Type: TEXT Property Parameters: Non-standard and language property parameters can be specified on this property. Conformance: The property can be specified within "VEVENT", "VTODO" or "VJOURNAL" calendar components. Description: 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 50] Internet-Draft iCalendar October 2005 the COMMA character (US-ASCII decimal 44). categories = "CATEGORIES" catparam ":" text *("," text) CRLF catparam = *( ; the following is optional, ; but MUST NOT occur more than once (";" languageparam ) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) The following are examples of categories. CATEGORIES:APPOINTMENT,EDUCATION CATEGORIES:MEETING 8.2.3. Classification Property Name: CLASS Purpose: This property defines the access classification for a calendar component. Value Type: TEXT Property Parameters: Non-standard property parameters can be specified on this property. Conformance: The property can be specified once in a "VEVENT", "VTODO" or "VJOURNAL" calendar components. Description: 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 51] Internet-Draft iCalendar October 2005 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. Formal Definition: The property is defined by the following notation: class = "CLASS" classparam ":" classvalue CRLF classparam = *(";" xparam) classvalue = "PUBLIC" / "PRIVATE" / "CONFIDENTIAL" / iana-token / x-name ;Default is PUBLIC Example: The following is an example of this property: CLASS:PUBLIC 8.2.4. Comment Property Name: COMMENT Purpose: This property specifies non-processing information intended to provide a comment to the calendar user. Value Type: TEXT Property Parameters: Non-standard, alternate text representation and language property parameters can be specified on this property. Conformance: This property can be specified in "VEVENT", "VTODO", "VJOURNAL", "VTIMEZONE" or "VFREEBUSY" calendar components. Description: The property can be specified multiple times. Desruisseaux & Stoner Expires April 14, 2006 [Page 52] Internet-Draft iCalendar October 2005 Formal Definition: The property is defined by the following notation: comment = "COMMENT" commparam ":" text CRLF commparam = *( ; the following are optional, ; but MUST NOT occur more than once (";" altrepparam) / (";" languageparam) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) Example: The following is an example of this property: COMMENT:The meeting really needs to include both ourselves and the customer. We can't hold this meeting without them. As a matter of fact\, the venue for the meeting ought to be at their site. - - John 8.2.5. Description Property Name: DESCRIPTION Purpose: This property provides a more complete description of the calendar component, than that provided by the "SUMMARY" property. Value Type: TEXT Property Parameters: Non-standard, alternate text representation and language property parameters can be specified on this property. Conformance: 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. Description: 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 more textual journal entries. This property is used in the "VALARM" calendar component to capture Desruisseaux & Stoner Expires April 14, 2006 [Page 53] Internet-Draft iCalendar October 2005 the display text for a DISPLAY category of alarm, to capture the body text for an EMAIL category of alarm and to capture the argument string for a PROCEDURE category of alarm. Formal Definition: The property is defined by the following notation: description = "DESCRIPTION" descparam ":" text CRLF descparam = *( ; the following are optional, ; but MUST NOT occur more than once (";" altrepparam) / (";" languageparam) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) Example: The following is an example of the property with formatted line breaks in the property value: DESCRIPTION:Meeting to provide technical review for "Phoenix" design.\n Happy Face Conference Room. Phoenix design team MUST attend this meeting.\n RSVP to team leader. The following is an example of the property with folding of long lines: DESCRIPTION:Last draft of the new novel is to be completed for the editor's proof today. 8.2.6. Geographic Position Property Name: GEO Purpose: This property specifies information related to the global position for the activity specified by a calendar component. Value Type: FLOAT. The value MUST be two SEMICOLON separated FLOAT values. Property Parameters: Non-standard property parameters can be specified on this property. Desruisseaux & Stoner Expires April 14, 2006 [Page 54] Internet-Draft iCalendar October 2005 Conformance: This property can be specified in "VEVENT" or "VTODO" calendar components. Description: The 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 55] Internet-Draft iCalendar October 2005 The simple formula for converting degrees-minutes-seconds into decimal degrees is: decimal = degrees + minutes/60 + seconds/3600. Formal Definition: The property is defined by the following notation: geo = "GEO" geoparam ":" geovalue CRLF geoparam = *(";" xparam) geovalue = float ";" float ;Latitude and Longitude components Example: The following is an example of this property: GEO:37.386013;-122.082932 8.2.7. Location Property Name: LOCATION Purpose: The property defines the intended venue for the activity defined by a calendar component. Value Type: TEXT Property Parameters: Non-standard, alternate text representation and language property parameters can be specified on this property. Conformance: This property can be specified in "VEVENT" or "VTODO" calendar component. Description: 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 URI pointing to an LDAP server entry or a CID URI pointing to a MIME body part containing a vCard [RFC 2426] for the location. Desruisseaux & Stoner Expires April 14, 2006 [Page 56] Internet-Draft iCalendar October 2005 Format Definition: The property is defined by the following notation: location = "LOCATION locparam ":" text CRLF locparam = *( ; the following are optional, ; but MUST NOT occur more than once (";" altrepparam) / (";" languageparam) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) Example: The following are some examples of this property: LOCATION:Conference Room - F123, Bldg. 002 LOCATION;ALTREP="http://xyzcorp.com/conf-rooms/f123.vcf": Conference Room - F123, Bldg. 002 8.2.8. Percent Complete Property Name: PERCENT-COMPLETE Purpose: 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. Value Type: INTEGER Property Parameters: Non-standard property parameters can be specified on this property. Conformance: This property can be specified in a "VTODO" calendar component. Description: 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 57] Internet-Draft iCalendar October 2005 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. Format Definition: The property is defined by the following notation: percent = "PERCENT-COMPLETE" pctparam ":" integer CRLF pctparam = *(";" xparam) Example: The following is an example of this property to show 39% completion: PERCENT-COMPLETE:39 8.2.9. Priority Property Name: PRIORITY Purpose: The property defines the relative priority for a calendar component. Value Type: INTEGER Property Parameters: Non-standard property parameters can be specified on this property. Conformance: The property can be specified in a "VEVENT" or "VTODO" calendar component. Description: The 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 58) 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 58) is "LOW" priority. Desruisseaux & Stoner Expires April 14, 2006 [Page 58] Internet-Draft iCalendar October 2005 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 58) 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. Format Definition: The property is specified by the following notation: priority = "PRIORITY" prioparam ":" privalue CRLF ;Default is zero prioparam = *(";" xparam) privalue = integer ;Must be in the range [0..9] ; All other values are reserved for future use The following is an example of a property with the highest priority: PRIORITY:1 The following is an example of a property with a next highest priority: PRIORITY:2 Example: The following is an example of a property with no priority. This is equivalent to not specifying the "PRIORITY" property: PRIORITY:0 8.2.10. Resources Property Name: RESOURCES Purpose: This property defines the equipment or resources anticipated for an activity specified by a calendar entity.. Desruisseaux & Stoner Expires April 14, 2006 [Page 59] Internet-Draft iCalendar October 2005 Value Type: TEXT Property Parameters: Non-standard, alternate text representation and language property parameters can be specified on this property. Conformance: This property can be specified in "VEVENT" or "VTODO" calendar component. Description: 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). Format Definition: The property is defined by the following notation: resources = "RESOURCES" resrcparam ":" text *("," text) CRLF resrcparam = *( ; the following are optional, ; but MUST NOT occur more than once (";" altrepparam) / (";" languageparam) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) Example: The following is an example of this property: RESOURCES:EASEL,PROJECTOR,VCR RESOURCES;LANGUAGE=fr:1 raton-laveur 8.2.11. Free/Busy Time Type Parameter Name: FBTYPE Purpose: To specify the free or busy time type. Description: The 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 Desruisseaux & Stoner Expires April 14, 2006 [Page 60] Internet-Draft iCalendar October 2005 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. Format Definition: The property parameter is defined by the following notation: fbtypeparam = "FBTYPE" "=" ("FREE" / "BUSY" / "BUSY-UNAVAILABLE" / "BUSY-TENTATIVE" / x-name ; Some experimental iCalendar data type. / iana-token) ; Some other IANA registered iCalendar data type. Example: The following is an example of this parameter on a FREEBUSY property. FREEBUSY;FBTYPE=BUSY:19980415T133000Z/19980415T170000Z 8.2.12. Participation Status Parameter Name: PARTSTAT Purpose: To specify the participation status for the calendar user specified by the property. Description: 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 61] Internet-Draft iCalendar October 2005 Format Definition: The property parameter is defined by the following notation: partstatparam = "PARTSTAT" "=" ("NEEDS-ACTION" ; Event needs action / "ACCEPTED" ; Event accepted / "DECLINED" ; Event declined / "TENTATIVE" ; Event tentatively ; accepted / "DELEGATED" ; Event delegated / x-name ; Experimental status / iana-token) ; Other IANA registered ; status ; These are the participation statuses for a "VEVENT". ; Default is NEEDS-ACTION partstatparam /= "PARTSTAT" "=" ("NEEDS-ACTION" ; To-do needs action / "ACCEPTED" ; To-do accepted / "DECLINED" ; To-do declined / "TENTATIVE" ; To-do tentatively ; accepted / "DELEGATED" ; To-do delegated / "COMPLETED" ; To-do completed. ; COMPLETED property has ;date/time completed. / "IN-PROCESS" ; To-do in process of ; being completed / x-name ; Experimental status / iana-token) ; Other IANA registered ; status ; These are the participation statuses for a "VTODO". Default is ; NEEDS-ACTION partstatparam /= "PARTSTAT" "=" ("NEEDS-ACTION" ; Journal needs action / "ACCEPTED" ; Journal accepted / "DECLINED" ; Journal declined / x-name ; Experimental status / iana-token) ; Other IANA registered ; status ; These are the participation statuses for a "VJOURNAL". ; Default is NEEDS-ACTION Desruisseaux & Stoner Expires April 14, 2006 [Page 62] Internet-Draft iCalendar October 2005 Example: ATTENDEE;PARTSTAT=DECLINED:MAILTO:jsmith@host.com 8.2.13. Status Property Name: STATUS Purpose: This property defines the overall status or confirmation for the calendar component. Value Type: TEXT Property Parameters: Non-standard property parameters can be specified on this property. Conformance: This property can be specified in "VEVENT", "VTODO" or "VJOURNAL" calendar components. Description: 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 63] Internet-Draft iCalendar October 2005 Format Definition: The property is defined by the following notation: status = "STATUS" statparam] ":" statvalue CRLF statparam = *(";" xparam) statvalue = "TENTATIVE" ;Indicates event is ;tentative. / "CONFIRMED" ;Indicates event is ;definite. / "CANCELLED" ;Indicates event was ;cancelled. ;Status values for a "VEVENT" statvalue =/ "NEEDS-ACTION" ;Indicates to-do needs action. / "COMPLETED" ;Indicates to-do completed. / "IN-PROCESS" ;Indicates to-do in process of / "CANCELLED" ;Indicates to-do was cancelled. ;Status values for "VTODO". statvalue =/ "DRAFT" ;Indicates journal is draft. / "FINAL" ;Indicates journal is final. / "CANCELLED" ;Indicates journal is removed. ;Status values for "VJOURNAL". Example: The following is an example of this property for a "VEVENT" calendar component: STATUS:TENTATIVE The following is an example of this property for a "VTODO" calendar component: STATUS:NEEDS-ACTION The following is an example of this property for a "VJOURNAL" calendar component: STATUS:DRAFT 8.2.14. Summary Property Name: SUMMARY Purpose: This property defines a short summary or subject for the calendar component. Value Type: TEXT Desruisseaux & Stoner Expires April 14, 2006 [Page 64] Internet-Draft iCalendar October 2005 Property Parameters: Non-standard, alternate text representation and language property parameters can be specified on this property. Conformance: The property can be specified in "VEVENT", "VTODO", "VJOURNAL" or "VALARM" calendar components. Description: 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. Format Definition: The property is defined by the following notation: summary = "SUMMARY" summparam ":" text CRLF summparam = *( ; the following are optional, ; but MUST NOT occur more than once (";" altrepparam) / (";" languageparam) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) Example: The following is an example of this property: SUMMARY:Department Party 8.2.15. Date and Time Component Properties The following properties specify date and time related information in calendar components. 8.2.15.1. Date/Time Completed Property Name: COMPLETED Purpose: This property defines the date and time that a to-do was actually completed. Value Type: DATE-TIME Desruisseaux & Stoner Expires April 14, 2006 [Page 65] Internet-Draft iCalendar October 2005 Property Parameters: Non-standard property parameters can be specified on this property. Conformance: The property can be specified in a "VTODO" calendar component. Description: The date and time MUST be in a UTC format. Format Definition: The property is defined by the following notation: completed = "COMPLETED" compparam ":" date-time CRLF compparam = *(";" xparam) Example: The following is an example of this property: COMPLETED:19960401T235959Z 8.2.15.2. Date/Time End Property Name: DTEND Purpose: This property specifies the date and time that a calendar component ends. Value Type: The default value type is DATE-TIME. The value type can be set to a DATE value type. Property Parameters: Non-standard, value data type, time zone identifier property parameters can be specified on this property. Conformance: This property can be specified in "VEVENT" or "VFREEBUSY" calendar components. Description: Within the "VEVENT" calendar component, this property defines the date and time by which the event ends. The value MUST be later in time than the value of the "DTSTART" property. 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. Desruisseaux & Stoner Expires April 14, 2006 [Page 66] Internet-Draft iCalendar October 2005 Format Definition: The property is defined by the following notation: dtend = "DTEND" dtendparam":" dtendval CRLF dtendparam = *( ; the following are optional, ; but MUST NOT occur more than once (";" "VALUE" "=" ("DATE-TIME" / "DATE")) / (";" tzidparam) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) dtendval = date-time / date ;Value MUST match value type Example: The following is an example of this property: DTEND:19960401T235959Z DTEND;VALUE=DATE:19980704 8.2.15.3. Date/Time Due Property Name: DUE Purpose: This property defines the date and time that a to-do is expected to be completed. Value Type: The default value type is DATE-TIME. The value type can be set to a DATE value type. Property Parameters: Non-standard, value data type, time zone identifier property parameters can be specified on this property. Conformance: The property can be specified once in a "VTODO" calendar component. Description: The value MUST be a date/time equal to or after the DTSTART value, if specified. Desruisseaux & Stoner Expires April 14, 2006 [Page 67] Internet-Draft iCalendar October 2005 Format Definition: The property is defined by the following notation: due = "DUE" dueparam":" dueval CRLF dueparam = *( ; the following are optional, ; but MUST NOT occur more than once (";" "VALUE" "=" ("DATE-TIME" / "DATE")) / (";" tzidparam) / ; the following is optional, ; and MAY occur more than once *(";" xparam) ) dueval = date-time / date ;Value MUST match value type Example: The following is an example of this property: DUE:19980430T235959Z 8.2.15.4. Date/Time Start Property Name: DTSTART Purpose: This property specifies when the calendar component begins. Value Type: 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. Property Parameters: Non-standard, value data type, time zone identifier property parameters can be specified on this property. Conformance: This property can be specified in the "VEVENT", "VTODO", "VFREEBUSY", or "VTIMEZONE" calendar components. Description: Within the "VEVENT" calendar component, this property defines the start date and time for the event. The property is REQUIRED in "VEVENT" calendar components. Events can have a start date/time but no end date/time. In that case, the event does not Desruisseaux & Stoner Expires April 14, 2006 [Page 68] Internet-Draft iCalendar October 2005 take up any time. 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 "VTIMEZONE" calendar component, this property defines the effective start date and time for a time zone specification. This property is REQUIRED within each STANDARD and DAYLIGHT part included in "VTIMEZONE" calendar components and MUST be specified as a local DATE-TIME without the "TZID" property parameter. Format Definition: The property is defined by the following notation: dtstart = "DTSTART" dtstparam ":" dtstval CRLF dtstparam = *( ; the following are optional, ; but MUST NOT occur more than once (";" "VALUE" "=" ("DATE-TIME" / "DATE")) / (";" tzidparam) / ; the following is optional, ; and MAY occur more than once *(";" xparam) ) dtstval = date-time / date ;Value MUST match value type Example: The following is an example of this property: DTSTART:19980118T073000Z 8.2.15.5. Duration Property Name: DURATION Purpose: The property specifies a positive duration of time. Value Type: DURATION Desruisseaux & Stoner Expires April 14, 2006 [Page 69] Internet-Draft iCalendar October 2005 Property Parameters: Non-standard property parameters can be specified on this property. Conformance: The property can be specified in "VEVENT", "VTODO", "VFREEBUSY" or "VALARM" calendar components. Description: 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 "VFREEBUSY" calendar component the property may be used to specify the interval of free time being requested. In a "VALARM" calendar component the property may be used to specify the delay period prior to repeating an alarm. Format Definition: The property is defined by the following notation: duration = "DURATION" durparam ":" dur-value CRLF ;consisting of a positive duration of time. durparam = *(";" xparam) Example: The following is an example of this property that specifies an interval of time of 1 hour and zero minutes and zero seconds: DURATION:PT1H0M0S The following is an example of this property that specifies an interval of time of 15 minutes. DURATION:PT15M 8.2.15.6. Free/Busy Time Property Name: FREEBUSY Purpose: The property defines one or more free or busy time intervals. Value Type: PERIOD. The date and time values MUST be in an UTC time format. Property Parameters: Non-standard or free/busy time type property parameters can be specified on this property. Conformance: The property can be specified in a "VFREEBUSY" calendar component. Desruisseaux & Stoner Expires April 14, 2006 [Page 70] Internet-Draft iCalendar October 2005 Property Parameter: "FBTYPE" and non-standard parameters can be specified on this property. Description: 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 SHOULD all be of the same "FBTYPE" property parameter type (e.g., all values of a particular "FBTYPE" listed together in a single property). Format Definition: The property is defined by the following notation: freebusy = "FREEBUSY" fbparam ":" fbvalue CRLF fbparam = *( ; the following is optional, ; but MUST NOT occur more than once (";" fbtypeparam) / ; the following is optional, ; and MAY occur more than once (";" xparam) ) fbvalue = period *["," period] ;Time value MUST be in the UTC time format. Example: The following are some examples of this property: FREEBUSY;FBTYPE=BUSY-UNAVAILABLE:19970308T160000Z/PT8H30M FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H, 19970308T230000Z/19970309T000000Z Desruisseaux & Stoner Expires April 14, 2006 [Page 71] Internet-Draft iCalendar October 2005 8.2.15.7. Time Transparency Property Name: TRANSP Purpose: This property defines whether an event is transparent or not to busy time searches. Value Type: TEXT Property Parameters: Non-standard property parameters can be specified on this property. Conformance: This property can be specified once in a "VEVENT" calendar component. Description: 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. Format Definition: The property is specified by the following notation: transp = "TRANSP" tranparam ":" transvalue CRLF tranparam = *(";" xparam) transvalue = "OPAQUE" ;Blocks or opaque on busy time searches. / "TRANSPARENT" ;Transparent on busy time searches. ;Default value is OPAQUE Example: The following is an example of this property for an event that is transparent or does not block on free/busy time searches: TRANSP:TRANSPARENT The following is an example of this property for an event that is opaque or blocks on free/busy time searches: TRANSP:OPAQUE Desruisseaux & Stoner Expires April 14, 2006 [Page 72] Internet-Draft iCalendar October 2005 8.2.16. Time Zone Component Properties The following properties specify time zone information in calendar components. 8.2.16.1. Time Zone Identifier Property Name: TZID Purpose: This property specifies the text value that uniquely identifies the "VTIMEZONE" calendar component. Value Type: TEXT Property Parameters: Non-standard property parameters can be specified on this property. Conformance: This property MUST be specified in a "VTIMEZONE" calendar component. Description: This is the label by which a time zone calendar component is referenced by any iCalendar properties whose data 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 Olson database [TZ]. The specification of globally unique time zone identifiers is not addressed by this document and is left for future study. Format Definition: This property is defined by the following notation: tzid = "TZID" tzidpropparam ":" [tzidprefix] text CRLF tzidpropparam = *(";" xparam) ;tzidprefix = "/" ; Defined previously. Just listed here for reader convenience. Desruisseaux & Stoner Expires April 14, 2006 [Page 73] Internet-Draft iCalendar October 2005 Example: The following are examples of non-globally unique time zone identifiers: TZID:US-Eastern TZID:California-Los_Angeles The following is an example of a fictitious globally unique time zone identifier: TZID:/US-New_York-New_York 8.2.16.2. Time Zone Name Property Name: TZNAME Purpose: This property specifies the customary designation for a time zone description. Value Type: TEXT Property Parameters: Non-standard and language property parameters can be specified on this property. Conformance: This property can be specified in a "VTIMEZONE" calendar component. Description: This property may be specified in multiple languages; in order to provide for different language requirements. Format Definition: This property is defined by the following notation: tzname =