HTTP/1.1 200 OK Date: Tue, 09 Apr 2002 01:24:13 GMT Server: Apache/1.3.20 (Unix) Last-Modified: Tue, 07 Apr 1998 05:44:26 GMT ETag: "2e7a2e-3c7e3-3529bd3a" Accept-Ranges: bytes Content-Length: 247779 Connection: close Content-Type: text/plain Network Working Group Frank Dawson, Lotus Internet Draft Derik Stenerson, Microsoft March 13, 1998 Expires September 1998 Internet Calendaring and Scheduling Core Object Specification (iCalendar) Status of this Memo This memo is an Internet-Draft. 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. Internet-Drafts MAY be updated, replaced, or made obsolete by other documents at any time. It is not appropriate to use Internet- Drafts as reference material or to cite them other than as a "working draft" or "work in progress". To learn the current status of any Internet-Draft, please check the 1id-abstracts.txt listing contained in the Internet-Drafts Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). Distribution of this memo is unlimited. Copyright (C) The Internet Society 1997. All Rights Reserved. Abstract There is a clear need to provide and deploy interoperable calendaring and scheduling services for the Internet. Current group scheduling and Personal Information Management (PIM) products are being extended for use across the Internet, today, in proprietary ways. This memo has been defined to provide the definition of a common format for openly exchanging calendaring and scheduling information across the Internet. This memo is formatted as a registration for a MIME media type per [RFC 2048]. However, the format in this memo is equally applicable for use outside of a MIME message content type. The proposed media type value is ''text/calendar''. This string would label a media type containing calendaring and scheduling information encoded as text characters formatted in a manner outlined below. This MIME media type provides a standard content type for capturing calendar event, to-do and journal entry information. It also can be used to convey free/busy time information. The content type is suitable as a MIME message entity that can be transferred over MIME based email systems, using HTTP or some other Internet transport. In Dawson/Stenerson 1 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 addition, the content type is useful as an object for interactions between desktop applications using the operating system clipboard, drag/drop or file systems capabilities. This memo is based on the earlier work of the vCalendar specification for the exchange of personal calendaring and scheduling information. In order to avoid confusion with this referenced work, this memo is to be known as the iCalendar specification. Readers may also wish to refer to the calendaring and scheduling model defined in [] for a description of this Internet application. This memo defines the format for specifying iCalendar object methods. An iCalendar object method is a set of usage constraints for the iCalendar object. For example, these methods might define scheduling messages that request an event be scheduled, reply to an event request, send a cancellation notice for an event, modify or replace the definition of an event, provide a counter proposal for an original event request, delegate an event request to another individual, request free or busy time, reply to a free or busy time request, or provide similar scheduling messages for a to-do or journal entry calendar component. The iCalendar Transport-indendent Interoperability Protocol (iTIP) defined in [ITIP] is one such scheduling protocol. Dawson/Stenerson 2 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Table of Contents 1 Introduction.........................................................8 2 Basic Grammar and Conventions........................................8 2.1 Formatting Conventions ...........................................9 2.2 Related Memos ...................................................10 3 TEXT/CALENDAR Registration Information..............................10 4 iCalendar Object Specification......................................13 4.1 Content Lines ...................................................13 4.1.1 List and Field Separators ....................................16 4.1.2 Multiple Values ..............................................16 4.1.3 Binary Content ...............................................17 4.1.4 Character Set ................................................17 4.2 Property Parameters .............................................17 4.2.1 Alternate Text Representation ................................18 4.2.2 Inline Encoding ..............................................19 4.2.3 Language .....................................................19 4.2.4 Time Zone Identifier .........................................20 4.2.5 Value Data Types .............................................21 4.3 Property Value Data Types .......................................21 4.3.1 Binary .......................................................22 4.3.2 Boolean ......................................................22 4.3.3 Calendar User Address ........................................23 4.3.4 Date .........................................................23 4.3.5 Date-Time ....................................................24 4.3.6 Duration .....................................................25 4.3.7 Float ........................................................26 4.3.8 Integer ......................................................27 4.3.9 Period of Time ...............................................27 4.3.10 Recurrence Rule .............................................28 4.3.11 Text ........................................................33 4.3.12 Time ........................................................34 4.3.13 URI .........................................................36 4.3.14 UTC Offset ..................................................36 4.4 iCalendar Object ................................................37 4.5 Property ........................................................38 4.6 Calendar Components .............................................38 4.6.1 Event Component ..............................................38 4.6.2 To-do Component ..............................................40 4.6.3 Journal Component ............................................41 4.6.4 Free/Busy Component ..........................................43 4.6.5 Timezone Component ...........................................45 4.6.6 Alarm Component ..............................................50 4.7 Calendar Properties .............................................53 4.7.1 Calendar Scale ...............................................54 4.7.2 Method .......................................................54 4.7.3 Product Identifier ...........................................55 4.7.4 Version ......................................................56 4.8 Component Properties ............................................56 4.8.1 Descriptive Component Properties .............................56 4.8.1.1 Attachment ...............................................56 4.8.1.2 Categories ...............................................57 Dawson/Stenerson 3 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 4.8.1.3 Classification ...........................................58 4.8.1.4 Comment ..................................................59 4.8.1.5 Description ..............................................59 4.8.1.6 Geographic Position ......................................60 4.8.1.7 Location .................................................61 4.8.1.8 Percent Complete .........................................61 4.8.1.9 Priority .................................................62 4.8.1.10 Resources ...............................................63 4.8.1.11 Status ..................................................64 4.8.1.12 Summary .................................................65 4.8.2 Date and Time Component Properties ...........................66 4.8.2.1 Date/Time Completed ......................................66 4.8.2.2 Date/Time End ............................................66 4.8.2.3 Date/Time Due ............................................67 4.8.2.4 Date/Time Start ..........................................68 4.8.2.5 Duration .................................................69 4.8.2.6 Free/Busy Time ...........................................69 4.8.2.7 Time Transparency ........................................71 4.8.3 Time Zone Component Properties ...............................72 4.8.3.1 Time Zone Identifier .....................................72 4.8.3.2 Time Zone Name ...........................................72 4.8.3.3 Time Zone Offset From ....................................73 4.8.3.4 Time Zone Offset To ......................................74 4.8.3.5 Time Zone URL ............................................74 4.8.4 Relationship Component Properties ............................75 4.8.4.1 Attendee .................................................75 4.8.4.2 Contact ..................................................78 4.8.4.3 Organizer ................................................79 4.8.4.4 Recurrence ID ............................................80 4.8.4.5 Related To ...............................................81 4.8.4.6 Uniform Resource Locator .................................82 4.8.4.7 Unique Identifier ........................................83 4.8.5 Recurrence Component Properties ..............................84 4.8.5.1 Exception Date/Times .....................................84 4.8.5.2 Exception Rule ...........................................85 4.8.5.3 Recurrence Date/Times ....................................86 4.8.5.4 Recurrence Rule ..........................................88 4.8.6 Alarm Component Properties ...................................95 4.8.6.1 Alarm Type ...............................................96 4.8.6.2 Repeat Count .............................................96 4.8.6.3 Trigger ..................................................97 4.8.7 Change Management Component Properties .......................98 4.8.7.1 Date/Time Created ........................................98 4.8.7.2 Date/Time Stamp ..........................................99 4.8.7.3 Last Modified ............................................99 4.8.7.4 Sequence Number .........................................100 4.8.8 Miscellaneous Component Properties ..........................101 4.8.8.1 Non-standard Properties .................................101 4.8.8.2 Request Status ..........................................102 5 iCalendar Object Examples..........................................103 6 Recommended Practices..............................................107 7 Registration of Content Type Elements..............................107 7.1 Registration of New and Modified iCalendar Object Methods ......107 7.2 Registration of New Properties .................................108 Dawson/Stenerson 4 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 7.2.1 Define the property .........................................108 7.2.2 Post the Property definition ................................109 7.2.3 Allow a comment period ......................................109 7.2.4 Submit the property for approval ............................109 7.3 Property Change Control ........................................109 8 References.........................................................109 9 Acknowledgments....................................................111 10 Author's Address..................................................111 11 Full Copyright Statement..........................................112 Dawson/Stenerson 5 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 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 content type for exchanging electronic calendaring and scheduling information. The Internet Calendaring and Scheduling Core Object Specification, or iCalendar, allows for the capture and exchange of information normally stored within a calendaring and scheduling application; such as a Personal Information Manager (PIM) or a Group Scheduling product. The calendaring and scheduling model, defined in the [ICMS], is a useful reference to terms and the general framework of this Internet application. The iCalendar format is suitable as an exchange format between applications or systems. The format is defined in terms of a MIME content type. This will enable the object to be exchanged using several transports, including but not limited to SMTP, HTTP, a file system, desktop interactive protocols such as the use of a memory- based clipboard or drag/drop interactions, point-to-point asynchronous communication, wired-network transport, or some form of unwired transport such as infrared might also be used. The memo also provides for the definition of iCalendar object methods that will map this content type to a set of messages for supporting calendaring and scheduling operations such as requesting, replying to, modifying, and canceling meetings or appointments, to-dos and journal entries. The iCalendar object methods can be used to define other calendaring and scheduling operations such a requesting for and replying with free/busy time data. Such a scheduling protocol is defined in the iCalendar Transport-independent Interoperability Protocol (iTIP) defined in [ITIP]. The memo also includes a formal grammar for the content type based on the Internet ABNF defined in [RFC 2234]. 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. 2 Basic Grammar and Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this document are to be interoperated as described in [RFC 2119]. Dawson/Stenerson 6 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 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]. 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. All numeric and hexadecimal values used in this memo are given in decimal notation. All names of properties, property parameters, enumerated property values and property parameter values are case- insensitive. However, all other property values are case-sensitive, unless otherwise stated. Note: All indented editorial notes, such as this one, are intended to provide the reader with additional information that is not essential to the building of a conformant implementation of the specifications of this memo. The information is provided to highlight a particular feature or characteristic of the specifications. The format for the iCalendar object is based on the syntax of the [MIME DIR] content type. While the iCalendar object is not a profile of the [MIME DIR] content type, it does reuse a number of the elements from the [MIME DIR] specification. 2.1 Formatting Conventions The mechanisms defined in this memo are defined in propose. 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 [ICMS], core object (this memo) or interoperability protocol [ITIP] some formatting conventions have been used. Calendaring and scheduling roles defined by [ICMS] 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. 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 lower case, quoted-strings of text, Dawson/Stenerson 7 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 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. 2.2 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 parameters. [ICMS] - specifies a common terminology and abstract model; [ITIP] - specifies an interoperability protocol for scheduling between different implementations; [IMIP] specifies an Internet email binding for [ITIP]; [IRIP] - specifies an Internet real time protocol 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. 3 TEXT/CALENDAR Registration Information The Calendaring and Scheduling Core Object Specification is intended for use as a MIME content type. However, the implementation of the memo is in no way limited solely as a MIME content type. The following text is intended to register this memo as the MIME content type "text/calendar". To: ietf-types@uninett.no Subject: Registration of MIME content type text/calendar. MIME media type name: text MIME subtype name: calendar Required parameters: none Optional parameters: charset, method and component The "charset" parameter is defined in [RFC 2046] for other body parts. It is used to identify the default character set used within the body part. Dawson/Stenerson 8 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 The "method" parameter is used to convey the iCalendar object method or transaction semantics for the calendaring and scheduling information. It also is an identifier for the restricted set of properties and values that the iCalendar object consists of. The parameter is to be used as a guide for applications interpreting the information contained within the body part. It SHOULD NOT be used to exclude or require particular pieces of information unless the identified method definition specifically calls for this behavior. Unless specifically forbidden by a particular method definition, a text/calendar content type MAY contain any set of properties permitted by the Calendaring and Scheduling Core Object Specification. The "method" parameter MUST be the same value as that specified in the "METHOD" component property in the iCalendar object. If one is present, the other must also be present. The value for the "method" parameter is defined as follows: method = 1*(ALPHA / DIGIT / "-") ; IANA registered iCalendar object method The "component" parameter conveys the type of iCalendar calendar component within the body part. If the iCalendar object contains more than one calendar component, then different components are each specified once in a comma-separated list of values. The value for the "component" parameter is defined as follows: component = ("VEVENT" / "VTODO" / "VJOURNAL" / "VFREEBUSY" / "VTIMEZONE" / x-name / iana-token) ["," [WSP] component] Optional content header fields: Any header fields defined by [RFC 2045]. Encoding considerations: This MIME content type can contain 8bit characters, so the use of quoted-printable or base64 MIME content- transfer-encodings MAY be necessary when iCalendar objects are transferred across protocols restricted to the 7bit repertoire. Note that a text valued property in the content entity MAY also have content encoding of special characters using a BACKSLASH character (ASCII decimal 92) escapement technique. This means that content values MAY end up encoded twice. Security considerations: SPOOFING - - In this memo, the "Organizer" is the only person authorized to make changes to an existing "VEVENT", "VTODO", "VJOURNAL" calendar component and redistribute the updates to the "Attendees". An iCalendar object that maliciously changes or cancels an existing "VEVENT", "VTODO" or "VJOURNAL" or "VFREEBUSY" calendar component MAY be constructed by someone other than the "Organizer" and sent to the "Attendees". In addition in this memo, other than the "Organizer", an "Attendee" of a "VEVENT", "VTODO", "VJOURNAL" calendar component is the only other person authorized to update any parameter associated with their "ATTENDEE" property and send it to the "Organizer". An Dawson/Stenerson 9 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 iCalendar object that maliciously changes the "ATTENDEE" parameters MAY be constructed by someone other than the real "Attendee" and sent to the "Organizer". PROCEDURAL ALARMS - - An iCalendar object can be created that contains a "VEVENT" and "VTODO" calendar component with an "VALARM" calendar components. The "VALARM" calendar component MAY be of type PROCEDURE and MAY have an attachment containing some sort of executable program. Implementations that incorporate these types of alarms are subject to any virus or malicious attack that MAY occur as a result of executing the attachment. ATTACHMENTS - - An iCalendar object MAY include references to Uniform Resource Locators that MAY be programmed resources. Implementers and users of this memo should be aware of the network security implications of accepting and parsing such information. In addition, the security considerations observed by implementations of electronic mail systems should be followed for this memo. Interoperability considerations: This MIME content type is intended to define a common format for conveying calendaring and scheduling information between different systems. It is heavily based on the earlier [VCAL] industry specification. Applications which use this media type: This content-type is designed for widespread use by Internet calendaring and scheduling applications. In addition, applications in the workflow and document management area may find this content-type applicable. The [ITIP], [IMIP] and [IRIP] Internet protocols directly use this content-type also. Future work on an Internet calendar access protocol will utilize this content-type too. Additional information: This memo defines this content-type. Magic numbers: None. File extensions: The file extension of "ics" is to be used to designate a file containing an arbitrary set of calendaring and scheduling information consistent with this MIME content type. The file extension of "ifb" is to be used to designate a file containing free or busy time information consistent with this MIME content type. Macintosh file type codes: The file type code of "ical" is to be used in Apple MacIntosh operating system environments to designate a file containing calendaring and scheduling information consistent with this MIME media type. The file type code of "ifb" is to be used in Apple MacIntosh operating system environments to designate a file containing free or busy time information consistent with this MIME media type. Dawson/Stenerson 10 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Person & email address to contact for further information: Frank Dawson 6544 Battleford Drive Raleigh, NC 27613-3502 919-676-9515 (Telephone) 919-676-9564 (Data/Facsimile) Frank_Dawson@Lotus.com (Internet Mail) Derik Stenerson One Microsoft Way Redmond, WA 98052-6399 425-936-5522 (Telephone) 425-936-7329 (Facsimile) deriks@microsoft.com (Internet Mail) Intended usage: COMMON Author/change controller: Frank Dawson 6544 Battleford Drive Raleigh, NC 27613-3502 919-676-9515 (Telephone) 919-676-9564 (Data/Facsimile) Frank_Dawson@Lotus.com (Internet Mail) Derik Stenerson One Microsoft Way Redmond, WA 98052-6399 425-936-5522 (Telephone) 425-936-7329 (Facsimile) deriks@microsoft.com (Internet Mail) 4 iCalendar Object Specification The following sections define the details of a Calendaring and Scheduling Core Object Specification. This information is intended to be an integral part of the MIME content type registration. In addition, this information MAY be used independent of such content registration. In particular, this memo has direct applicability for use as a calendaring and scheduling exchange format in file-, memory- or network-based transport mechanisms. 4.1 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 (ASCII decimal 13, followed by ASCII decimal 10). Dawson/Stenerson 11 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Lines of text SHOULD NOT be longer than 75 characters, excluding the line break. Long content lines SHOULD be split into a multiple line representations using a line "folding" technique. That is, a long line MAY be split at any point by inserting a CRLF immediately followed by a single linear white space character (i.e., SPACE, ASCII decimal 32 or HTAB, 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. Can be represented as: DESCRIPTION:This is a lo ng description that exists on a long line. 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 characters SHOULD be folded according to the folding procedure described above. The content information associated with an iCalendar object is formatted using a syntax similar to that defined by [MIME DIR]. That is, the content information consists of one or more CRLF-separated content lines. The following notation defines the defines the lines of content in an iCalendar object: contentline = name *(";" [WSP] 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 characters 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 Dawson/Stenerson 12 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 x-name = "X-" 1*(ALPHA / DIGIT / "-") ; Reservered for experimental use. Not intended for use in ; released products. 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 param-value = paramtext / quoted-string paramtext = *SAFE-CHAR value = *VALUE-CHAR quoted-string = DQUOTE *qtext DQUOTE qtext = QSAFE-CHAR / QUOTED-CHAR NON-ASCII = %x80-FF ; Use restricted by charset parameter ; on outer MIME object (UTF-8 preferred) QSAFE-CHAR = WSP / %x21 / %x23-5B / %x5D-7E / NON-ASCII ; Any character except CTLs, DQUOTE, or "\" QUOTED-CHAR = "\" ("\" / "," / DQUOTE) ; \\ encodes \, \" encodes " SAFE-CHAR = WSP / %x21 / %x23-2B / %x2D-39 / %x3C-7E / NON-ASCII ; Any character except CTLs, DQUOTE, ";", ":", "," VALUE-CHAR = WSP / VCHAR / NON-ASCII ; Any textual character VCHAR = %x21-7E ; visible (printing) characters CR = %x0D ; carriage return LF = %x0A CRLF = CR LF ; Internet standard newline CTL = %x00-1F / %x7F ; Controls ALPHA = %x41-5A / %x61-7A ; A-Z / a-z Dawson/Stenerson 13 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 DIGIT = %x30-39 ; 0-9 DQUOTE = %x22 ; Quotation Mark WSP = SPACE / HTAB SPACE = %x20 HTAB = %x09 The property value component of a content line has a format that is property specific. Refer to the section describing each property for a definition of this format. 4.1.1 List and Field Separators List of values MAY be specified for property values or property parameter values. Each value in a list of values MUST be separated by a COMMA character (ASCII decimal 44). Some property values are defined in terms of multiple components. These structured property values MUST have their components separated by a SEMICOLON character (ASCII decimal 59). Lists of property parameters MAY be specified for a property. Each property parameter in a list of property parameters MUST be separated by a SEMICOLON character (ASCII decimal 59). Property parameters with values containing a COLON, a SEMICOLON or a COMMA character must be placed in quoted text string. For example, in the following properties a SEMICOLON is used to separate property parameters and property value fields. A COMMA is used to separate values. ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:MAILTO: jsmith@host.com RDATE;VALUE=DATE:19970304,19970504,19970704,19970904 4.1.2 Multiple Values Some properties defined in the iCalendar object MAY 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 (ASCII decimal 44). Dawson/Stenerson 14 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 4.1.3 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 MAY be included within an iCalendar object, but only after first encoding it into text using the "B" encoding method defined in [RFC 2047]. Support for inline binary content SHOULD be restricted to those applications requirements that necessitate conveying the complete calendaring and scheduling information within a single iCalendar object. 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;ENCODING=b;VALUE=binary:MIICajCCAdOgAwIBAgICBEUwDQYJKoZI hvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENv bW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlv biBTeXN0 <...remainder of "B" encoded binary data...> 4.1.4 Character Set There is not a property parameter to declare the character set used in a property value. The default character set for an iCalendar object is [UTF-8]. The "charset" Content-Type parameter MAY be used in MIME transports to specify any other IANA registered character set. 4.2 Property Parameters A property MAY have additional attributes associated with it. These "property parameters" contain meta information about the property or the property value. Property parameters MAY be used to specify the location of an alternate text representation for a property value, the language of a text property value or the data type of the property value. In addition, individual properties MAY define property-specific parameters that apply only to that property. Property parameter values that contain the COLON, SEMICOLON, COMMA or BACKSLASH character separators MUST be specified as quoted-string text values. For example: Dawson/Stenerson 15 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 DESCRIPTION;ALTREP="http://www.wiz.org":The Fall'98 Wild Wizards Conference - - Las Vegas, NV, USA Property parameter values that are not in quoted strings are case insensitive. The general property parameters defined by this memo are specified the following notation: parameter = altrepparm ;Alternate text representation / encodingparm ;Inline encoding / languageparm ;National language for text / tzidparm ;Reference to time zone object / valuetypeparm ;Property value data type / iana-token ;Some other IANA registered iCalendar parameter, such as those ;defined by an individual property. / x-name ;A non-standard, experimental parameter 4.2.1 Alternate Text Representation Parameter Name: ALTREP Purpose: To specify an alternate text representation for the property value. Conformance: Optional Format Definition: The property parameter is defined by the following notation: altrepparm = "altrep" "=" DQUOTE uri DQUOTE Description: The parameter specifies a URI that points to an alternate representation for a textual property value. A property specifying this parameter MUST also include a value that reflects the default representation. This property parameter MAY include multiple values, separated by the COMMA character (ASCII decimal 44). The property parameter MAY only be specified in the "COMMENT", "CONTACT", "DESCRIPTION", "LOCATION" and "SUMMARY" properties. Example: DESCRIPTION;ALTREP="CID:":Project XYZ Review Meeting will include the following agenda items: (a) Market Overview, (b) Finances, (c) Project Management The "ALTREP" property parameter value might point to a "text/html" content portion. Dawson/Stenerson 16 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Content-Type:text/html Content-Id:

Project XYZ Review Meeting will include the following agenda items:

  • Market Overview
  • Finances
  • Project Management

    • 4.2.2 Inline Encoding Parameter Name: ENCODING Purpose: To specify an alternate inline encoding for the property value. Conformance: Required, if the inline encoding is not "8bit". Format Definition: The property parameter is defined by the following notation: encodingparm = "encoding" "=" "8bit" ;"8bit" text encoding is defined in [RFC 2045] / "b" ;"b" binary encoding format is defined in [RFC 2047] / iana-token ;Some other IANA registered iCalendar encoding type / x-name ;A non-standard, experimental encoding type Description: The "ENCODING property parameter is an OPTIONAL property parameter. It identifies the inline encoding used in a property value. The default encoding type is "8bit", corresponding to a property value consisting of text. The "b" encoding type corresponds to a property value encoded using the "B" encoding defined in [RFC 2047]. If the value type parameter is ";VALUE=BINARY", then the inline encoding parameter MUST be specified with the value ";ENCODING=B". 4.2.3 Language Parameter Name: LANGUAGE Purpose: To specify the national language for text values in a property or property parameter. Conformance: Optional. There is no default national language for a text value. Format Definition: The property parameter is defined by the following notation: languageparm = "language" "=" language language = Dawson/Stenerson 17 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Description: The parameter identifies the national language of the text in the property or property parameter value. The value of the "language" property parameter is that defined in [RFC 1766]. Note: For transport in a MIME entity, the Content-Language header field MAY be used to set the default language for the entire body part. Example: SUMMARY;LANGUAGE=us-EN:Company Holiday Party ATTENDEE;CN=Henri Weisz;LANGUAGE=ca-FR:hweisz@host.com 4.2.4 Time Zone Identifier Parameter Name: TZID Purpose: To specify the identifier for the time zone definition for a time value. Conformance: Optional Format Definition: This property parameter is defined by the following notation: tzidparm = "TZID" "=" [tzidprefix] paramtext CRLF tzidprefix = "/" Description: The parameter MAY only be used on the "DTSTART", "DTEND", "DUE", "EXDATE" and "RDATE " properties when either a DATE- TIME or TIME value type is specified. This property parameter specifies a text value which uniquely identifies the "VTIMEZONE" calendar component to be used when evalating the time portion of the property. The value of the TZID property parameter will be equal to the value of the TZID property for the matching "TIMEZONE" object. The presence of the SOLIDUS character (ASCII decimal 47) as a prefix, indicates that this TZID represents a unique ID in a globally defined time zone registry (when such registry is defined). The following are examples of this property parameter: DTSTART;TZID=America-New_York:19980119T020000 DTEND;TZID=America-New_York:19980119T030000 The TZID property parameter MUST NOT be applied to DATE-TIME nor TIME properties whose time values are specified in UTC. The use of local time in a DATE-TIME or TIME value without the TZID property parameter is to be interpreted as a local time value, regardless of the existence of "VTIMEZONE" calendar components in the iCalendar object. Dawson/Stenerson 18 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 For more information see the sections on the data types DATE-TIME and TIME. 4.2.5 Value Data Types Parameter Name: VALUE Purpose: To explicitly specify the data type format for a property value. Conformance: Optional if using the default value type in a property value. Otherwise, it is required. Format Definition: The "VALUE" property parameter is defined by the following notation: valuetypeparm = "value" "=" valuetype valuetype = "binary" / "boolean" / "cal-address" / "date" / "date-time" / "duration" / "float" / "integer" / "period" / "recur" / "text" / "time" / "uri" / "utc-offset" / x-name ;Some experimental iCalendar data type. / iana-token ;Some other IANA registered iCalendar data type. Description: The parameter is used to identify the data type and format of the property value. The property values MUST be of a single value type. For example, a "RDATE" property cannot have a combination of DATE-TIME and TIME value types. 4.3 Property Value Data Types The properties in an iCalendar object are strongly typed. The definition of each property restricts the value to be one of the value data types, or simply value types, defined in this section. The value type for a property will either be specified implicitly as the default value type or will be explicitly specified with the "VALUE" parameter. If the value type of a property is one of the alternate valid types, then it MUST be explicitly specified with the "VALUE" parameter. Dawson/Stenerson 19 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 4.3.1 Binary Value Name: BINARY Purpose: This value type is used to identify properties that contain a character encoding of inline binary data. For example, an inline attachment of an object code MAY BE included in an iCalendar object. Formal Definition: The value type is defined by the following notation: binary = *(4b-char) [b-end] ; A "B" encoded character string, as defined by [RFC 2047]. b-end = (2b-char "==") / (3b-char "=") b-char = ALPHA / DIGIT / "+" / "/" Description: Property values with this value type MUST also include the inline encoding parameter sequence of ";ENCODING=B". That is, all inline binary data MUST first be character encoded using the "B" encoding method defined in [RFC 2047]. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: The following is an abridged example of a "B" encoded binary value data. ATTACH;VALUE=BINARY:MIICajCCAdOgAwIBAgICBEUwDQYJKoZIhvcNAQEEBQA wdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlIENvbW11bmljYXRpb 25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvcm1hdGlvbiBTeXN0 <...remainder of "B" encoded binary data...> 4.3.2 Boolean Value Name: BOOLEAN Purpose: This value type is used to identify properties that contain either a "true" or "false" boolean value. Formal Definition: The value type is defind by the following notation: boolean = "TRUE" / "FALSE" Description: These values are case insensitive text. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: For example, any of the following are equivalent: TRANSP;VALUE=BOOLEAN:TRUE TRANSP;VALUE=BOOLEAN:true TRANSP;VALUE=BOOLEAN:TrUe Dawson/Stenerson 20 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 4.3.3 Calendar User Address Value Name: CAL-ADDRESS Purpose: This value type is used to identify properties that contain a calendar user address. Formal Definition: The value type is as defined by the following notation: cal-address = uri Description: The value is a URI as defined by [RFC 1738] or any other IANA registered form for a URI. When used to address an Internet email transport address for a calendar user, the value MUST be a MAILTO URI, as defined by [RFC 1738].No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: ATTENDEE;VALUE=CAL-ADDRESS:MAILTO:jane_doe@host.com 4.3.4 Date Value Name: DATE Purpose: This value type is used to identify values that contain a calendar date. Formal Definition: The value type is defined by the following notation: date = date-value *("," [WSP] date-value) date-value = date-fullyear date-month date-mday date-fullyear = 4DIGIT date-month = 2DIGIT ;01-12 date-mday = 2DIGIT ;01-28, 01-29, 01-30, 01-31 ;based on month/year Description: If the property permits, multiple "date" values MAY be specified using a COMMA character (ASCII decimal 44) separator character.The format for the value type is expressed as the [ISO 8601] complete representation, basic format for a calendar date. The textual format specifies a four-digit year, two-digit month, and two- digit day of the month. There are no separator characters between the year, month and day component text. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: The following represents July 14, 1997: Dawson/Stenerson 21 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 19970714 4.3.5 Date-Time Value Name: DATE-TIME Purpose: This value type is used to identify values that specify a precise calendar data and time of day. Formal Definition: The value type is defined by the following notation: date-time = dt-value *("," [WSP] dt-value) dt-value = date "T" time ;As specified above in date and time Description: If the property permits, multiple "date-time" values MAY be specified using a COMMA character (ASCII decimal 44) separator character. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. The "DATE-TIME" data type is used to identify values that contain a precise calendar date and time of day. The format is based on the [ISO 8601] complete representation, basic format for a calendar date and time of day. The text format is a concatenation of the "date", followed by the LATIN CAPITAL LETTER T character (ASCII decimal 84) time designator, followed by the "time" format. The "DATE-TIME" data type expresses time values in three forms: The form of date and time with UTC offset MUST NOT be used. For example, the following is not valid for a date-time value: DTSTART:19980119T230000-0800 FORM #1: DATE WITH LOCAL TIME The date with local time form is simply a date-time value that does not contain the UTC designator nor does it reference a time zone. For example, the following represents Janurary 18, 1998, at 11 PM: DTSTART:19980118T230000 Date-time values of this type are said to be "floating" and are not bound to any time zone in particular. They are used to represent the same hour, minute, and second value regardless of which time zone is currently being observed. For example, an event MAY be defined that indicates that an individual will be busy from 11:00 AM to 1:00 PM every day, no matter which timezone the person is in. In these cases, a local time MAY be specified. The recipient of an iCalendar object with a property value consisting of a local time, without any relative time zone information, should interpret the value as being fixed to whatever timezone the ATTENDEE is in at any given moment. This means that two ATTENDEEs may participate in the same event at Dawson/Stenerson 22 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 different UTC times; floating time should only be used where that is reasonable behavior. In most cases, a fixed time is desired. To properly communicate a fixed time in a property value, either UTC time or local time with time zone reference MUST be specified. The use of local time in a DATE-TIME value without the TZID property parameter is to be interpreted as a local time value, regardless of the existence of "VTIMEZONE" calendar components in the iCalendar object. FORM #2: DATE WITH UTC TIME The date with UTC time, or absolute time, is identified by a LATIN CAPITAL LETTER Z suffix character (ASCII decimal 90), the UTC designator, appended to the time value. For example, the following represents January 19, 1998, at 0700 UTC: DTSTART:19980119T070000Z The TZID property parameter MUST NOT be applied to DATE-TIME properties whose time values are specified in UTC. FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE The date and local time with reference to time zone information is identified by the use the TZID property parameter to reference the appropriate time zone definition. TZID is discussed in detail in the section on Time Zone. For example, the following represents 2 AM in New York on Janurary 19, 1998: DTSTART;TZID=America-New_York:19980119T020000 Example: The following represents July 14, 1997, at 1:30 PM in New York City in each of the three time formats, using the "DTSTART" property. DTSTART:19970714T133000 ;Local time DTSTART:19970714T153000Z ;UTC time DTSTART;TZID=America-NYC:19970714T133000 ;Local time and time ; zone reference 4.3.6 Duration Value Name: DURATION Purpose: This value type is used to identify properties that contain a duration of time. Formal Definition: The value type is defined by the following notation: duration = dur-value *("," [WSP] dur-value) Dawson/Stenerson 23 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 dur-value = (["+"] / "-") "P" (dur-date / dur-time / dur-week) dur-date = (dur-day) [dur-time] dur-time = "T" (dur-hour / dur-minute / dur-second) dur-week = 1*DIGIT "W" dur-hour = 1*DIGIT "H" [dur-minute] dur-minute = 1*DIGIT "M" [dur-second] dur-second = 1*DIGIT "S" dur-day = 1*DIGIT "D" Description: If the property permits, multiple "duration" values MAY be specified using a COMMA character (ASCII decimal 44) separator character.The format is expressed as the [ISO 8601] basic format for the duration of time. The format can represent durations in terms of years, months, days, hours, minutes, and seconds. No additional content value encoding (i.e., BACKSLASH character encoding) are defined for this value type. Example: A duration of 15 days, 5 hours, 30 minutes and 20 seconds would be: P15DT5H30M20S A duration of 7 weeks would be: P15DT5H30M20S 4.3.7 Float Value Name: FLOAT Purpose: This value type is used to identify properties that contain a real value number value. Formal Definition: The value type is defined by the following notation: float = float-value *("," [WSP] float-value) float-value = (["+"] / "-") 1*DIGIT ["." 1*DIGIT] Description: If the property permits, multiple "float" values MAY be specified using a COMMA character (ASCII decimal 44) separator character. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: Dawson/Stenerson 24 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 1000000.0000001 1.333 -3.14 4.3.8 Integer Value Name:INTEGER Purpose: This value type is used to identify properties that contain a signed integer value. Formal Definition: The value type is defined by the following notation: integer = integer-value *("," [WSP] integer-value) integer-value = (["+"] / "-") *DIGIT Description: If the property permits, multiple "integer" values MAY be specified using a COMMA character (ASCII decimal 44) separator character.The valid range for "integer" is -2147483648 to 2147483647. If the sign is not specified, then the value is assumed to be positive. If the property permits, multiple "integer" values MAY be specified using a COMMA character (ASCII decimal 44) separator character. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: 1234567890 -1234567890 +1234567890 432109876 4.3.9 Period of Time Value Name: PERIOD Purpose: This value type is used to identify values that contain a precise period of time. Formal Definition: The data type is defined by the following notation: period = period-value *("," [WSP] period-value) period-value = period-explicit / period-start period-explicit = date-time "/" date-time ;ISO 8601 complete representation basic format for a period of time ;consisting of a start and end. The start MUST be before the end. Dawson/Stenerson 25 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 period-start = date-time "/" duration ;ISO 8601 complete representation basic format for a period of time ;consisting of a start and duration of time. Description: If the property permits, multiple "period" values MAY be specified using a COMMA character (ASCII decimal 44) separator character. There are two forms of a period of time. A period of time MAY be identified by it's start and it's end. This format is expressed as the [ISO 8601] complete representation, basic format for "DATE-TIME" start of the period, followed by a SOLIDUS character (ASCII decimal 47), followed by the "DATE-TIME" of the end of the period. A period of time MAY also be defined by a start and a duration of time. The format is expressed as the [ISO 8601] complete representation, basic format for the "DATE-TIME" start of the period, followed by a SOLIDUS character (ASCII decimal 47), followed by the [ISO 8601] basic format for "DURATION" of the period. Example: The period starting at 18:00:00 UTC, on January 1, 1997 and ending at 07:00:00 UTC on January 2, 1997 would be: 19970101T180000Z/19970102T070000Z The period start at 18:00:00 on January 1, 1997 and lasting 5 hours and 30 minutes would be: 19970101T180000Z/PT5H30M No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. 4.3.10 Recurrence Rule Value Name: RECURR Purpose: This value type is used to identify properties that contain a recurrence rule specification. Formal Definition: The value type is defined by the following notation: recur = recur-value *("," [WSP] recur-value) recur-value = "FREQ"=freq ";" [("UNTIL" "=" enddate ";") / ("COUNT" "=" 1*DIGIT ";")] ["INTERVAL" "=" 1*DIGIT ";"] ["BYSECOND" "=" byseclist ";"] ["BYMINUTE" "=" byminlist ";"] ["BYHOUR" "=" byhrlist ";"] ["BYDAY" "=" bywdaylist ";"] ["BYMONTHDAY" "=" bymodaylist ";"] ["BYYEARDAY" "=" byyrdaylist ";"] ["BYWEEKNO" "=" bywknolist ";"] ["BYMONTH" "=" bymolist ";"] ["BYSETPOS" "=" bysplist ";"] Dawson/Stenerson 26 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 ["WKST" "=" weekday ";")] *(x-name "=" text) ";" ;Individual components MAY only be specified once. ;Rule components need not be specified in particular any order. freq = "SECONDLY" / "MINUTELY" / "HOURLY" / "DAILY" / "WEEKLY" / "MONTHLY" / "YEARLY" enddate = date enddate =/ date-time ;A UTC value byseclist = seconds / ( seconds *("," seconds) ) seconds = 1DIGIT / 2DIGIT ;0 to 59 byminlist = minutes / ( minutes *("," minutes) ) minutes = 1DIGIT / 2DIGIT ;0 to 59 byhrlist = hour / ( hour *("," hour) ) hour = 1DIGIT / 2DIGIT ;0 to 23 bywdaylist = weekdaynum / ( weekdaynum *("," weekdaynum) ) weekdaynum = [([plus] ordwk / minus ordwk)] weekday plus = "+" minus = "-" ordwk = 1DIGIT / 2DIGIT ;1 to 53 weekday = "SU" / "MO" / "TU" / "WE" / "TH" / "FR" / "SA" ;Corresponding to SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, ;FRIDAY, SATURDAY and SUNDAY days of the week. bymodaylist = monthdaynum / ( monthdaynum *("," monthdaynum) ) monthdaynum = ([plus] ordmoday) / (minus ordmoday) ordmoday = 1DIGIT / 2DIGIT ;1 to 31 byyrdaylist = yeardaynum / ( yeardaynum *("," yeardaynum) ) yeardaynum = ([plus] ordyrday) / (minus ordyrday) ordyrday = 1DIGIT / 2DIGIT / 3DIGIT ;1 to 366 bywknolist = weeknum / ( weeknum *("," weeknum) ) weeknum = ([plus] ordwk) / (minus ordwk) bymolist = monthnum / ( monthnum *("," monthnum) ) Dawson/Stenerson 27 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 monthnum = 1DIGIT / 2DIGIT ;1 to 12 bysplist = setposday / ( setposday *("," setposday) ) setposday = yeardaynum Description: If the property permits, multiple "recur" values MAY be specified using a COMMA character (ASCII decimal 44) separator character. The value type is a structured value consisting of a list of one or more recurrence grammar components. Each component is defined by a NAME=VALUE pair. The components are separated from each other by the SEMICOLON character (ASCII decimal 59). The components are not ordered in any particular sequence. Individual components MAY only be specified once. The FREQ component identifies the type of recurrence rule. This component MUST be specified in the recurrence rule. Valid values include SECONDLY, to specify repeating events based on an interval of a second or more; MINUTELY, to specify repeating events based on an interval of a minute or more; HOURLY, to specify repeating events based on an interval of an hour or more; DAILY, to specify repeating events based on an interval of a day or more; WEEKLY, to specify repeating events based on an interval of a week or more; MONTHLY, to specify repeating events based on an interval of a month or more; and YEARLY, to specify repeating events based on an interval of a year or more. The INTERVAL component contains a positive integer representing how often the recurrence rule repeats. The default value is "1" or every minute for a MINUTELY rule, every hour for a HOURLY rule, every day for a DAILY rule, every week for a WEEKLY rule, every month for a MONTHLY rule and every year for a YEARLY rule. The UNTIL component defines a date-time value which bounds the recurrence rule in an inclusive manner. If the value specified by UNTIL is synchronized with the specified recurrence, this date-time becomes the last instance of the recurrence. If not present, and the COUNT component is also not present, the RRULE is considered to repeat forever. The COUNT component defines the number of occurrences at which to range-bound the recurrence. This component is ignored if the "UNTIL" component is also present. The BYSECOND component specifies a COMMA character (ASCII decimal 44) separated list of seconds within a minute. Valid values are 0 to 59. The BYMINUTE component specifies a COMMA character (ASCII decimal 44) separated list of minutes within an hour. Valid values are 0 to 59. The BYHOUR component specifies a COMMA character (ASCII decimal 44) separated list of hours of the day. Valid values are 0 to 23. The BYDAY component specifies a COMMA character (ASCII decimal 44) separated list of days of the week; MO, indicates Monday; TU, Dawson/Stenerson 28 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 indicates Tuesday; WE, indicates Wednesday; TH, indicates Thursday; FR, indicates Friday; SA, indicates Saturday; SU, indicates Sunday. Each BYDAY value MAY also be preceded by a positive (+n) or negative (-n) integer. If present, this indicates the nth occurrence of the specific day within the MONTHLY or YEARLY RRULE. For example, within a MONTHLY rule, +1MO (or simply 1MO) represents the first Monday within the month, whereas -1MO represents the last Monday of the month. If an integer modifier is not present, it means all days of this type within the specified frequency. For example, within a MONTHLY rule, MO represents all Mondays within the month. The BYMONTHDAY component specifies a COMMA character (ASCII decimal 44) separated list of days of the month. Valid values are 1 to 31 or -31 to -1. Each BYMONTHDAY value MAY include a positive (+n) or negative (-n) integer. If present, this indicates the nth occurrence of the specific day of the month within the MONTHLY rule. If an integer modifier is not present, it means all days of this type within the specified frequency. For example, within a MONTHLY rule, -10 represents the tenth to the last day of the month. The BYYEARDAY component specifies a COMMA character (ASCII decimal 44) separated list of days of the year. Valid values are 1 to 366 or -366 to -1. For example, -1 represents the last day of the year (December 31st). The BYWEEKNO component specifies a comma-separated list of weeks of the year. Valid values are 1 to 53. This corresponds to weeks according to week numbering as defined in [ISO 8601]. That is, a week as "A seven day period within a calendar year, starting on a Monday and identified by its ordinal number within the year; the first calendar week of the year is the one that includes the first Thursday of that year." This component is only valid for YEARLY rules. Each BYWEEKNO value MAY include a positive (+n) or negative (-n) integer. If present, this indicates the nth occurrence of the specific week of the year within the YEARLY rule. If an integer modifier is not present, it means all days of this type within the specified frequency. For example, within a YEARLY rule, 3 represents the third week of the year. The BYMONTH component specifies a comma separated list of months of the year. Valid values are 1 to 12. The WKST component specifies the day on which the workweek starts. Valid values are MO, TU, WE, TH, FR, SA and SU. This is significant when a WEEKLY RRULE has an interval greater than 1, and a BYDAY component is specified. The default value is MO. The BYSETPOS component specifies a COMMA character (ASCII decimal 44) separated list of values which corresponds to the nth occurrence within the set of events specified by the rule. Valid values are 1 to Dawson/Stenerson 29 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 366 or -366 to -1. It MUST only be used in conjunction with another Byxxx component. For example "the last work day of the month" could be represented as: RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1 Each BYSETPOS value MAY include a positive (+n) or negative (-n) integer. If present, this indicates the nth occurrence of the specific occurrence within the set of events specified by the rule. If BYxxx component values are found which are beyond the available scope (ie, BYMONTHDAY=30 in February), they are simply ignored. Information, not contained in the rule, necessary to determine the various recurrence instance start time and dates are derived from the Start Time (DTSTART) entry attribute. For example, "FREQ=YEARLY;BYMONTH=1" doesn't specify a specific day within the month or a time. This information would be the same as what is specified for DTSTART. BYxxx components modify the recurrence in some manner. BYxxx components for a period of time which is the same or greater than the frequency generally reduce or limit the number of occurrences of the recurrence generated. For example, "FREQ=DAILY;BYMONTH=1" reduces the number of recurrence instances from all days (if BYMONTH tag is not present) to all days in January. BYxxx components for a period of time less than the frequency generally increase or expand the number of occurrences of the recurrence. For example, "FREQ=YEARLY;BYMONTH=1,2" increases the number of days within the yearly recurrence set from 1 (if BYMONTH tag is not present) to 2. If only one BYxxx component is specified in the recurrence rule, the list of "n" unique values would cause "n" occurrences of the recurrence within each specified frequency interval, where each unique list value is substituted in the appropriate date position within DTSTART for each such occurrence. If multiple BYxxx components are specified, then after evaluating the specified FREQ and INTERVAL components, the BYxxx components are applied to the current set of evaluated occurrences in the following order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY, BYDAY, BYHOUR, BYMINUTE, BYSECOND and BYSETPOS. Here is an example of evaluating multiple BYxxx components. DTSTART;TZID=EST=19970105T083000 RRULE:FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=SU;BYHOUR=8,9; BYMINUTE=30 First, the "INTERVAL=2" would be applied to "FREQ=YEARLY" to arrive at "every other year". Then, "BYMONTH=1" would be applied to arrive at "every January, every other year". Then, "BYDAY=SU" would be applied to arrive at "every Sunday in January, every other year". Then, "BYHOUR=8,9" would be applied to arrive at "every Sunday in Dawson/Stenerson 30 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 January at 8 AM and 9 AM, every other year". Then, "BYMINUTE=30" would be applied to arrive at "every Sunday in January at 8:30 AM and 9:30 AM, every other year". Similarly, if the BYMINUTE, BYHOUR, BYDAY, BYMONTHDAY or BYMONTH component were missing, the appropriate minute, hour, day or month would have been retrieved from the "DTSTART" property. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: The following is a rule which specifies 10 meetings which occur every other day: FREQ=DAILY;COUNT=10;INTERVAL=2 There are other examples specified in the "RRULE" specification. 4.3.11 Text Value Name: TEXT Purpose This value type is used to identify values that contain human readable text. Formal Definition: The value type is defined by the following notation: text = text-value *("," text-value) ; Folded according to folded-value syntax above or ; encoded according to param-value syntax above. text-value = *(SAFE-CHAR / ":" / DQUOTE / ESCAPED-CHAR) ESCAPED-CHAR = "\\" / "\;" / "\," / "\N" / "\n") ; \\ encodes \, \N or \n encodes newline ; \; encodes ;, \, encodes , NON-ASCII = %x80-FF ; use restricted by charset parameter ; on outer MIME object SAFE-CHAR = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B %x5D-7E / NON-ASCII ; Any character except CTLs, DQUOTE, ";", ":", "\", "," Description: If the property permits, multiple "text" values MAY be specified using a COMMA character (ASCII decimal 44) separator character. The character set and language in which the text is represented is controlled by the "LANGUAGE" property parameters. An intentional formatted text line break MAY only be included in a "TEXT" property value by representing the line break with the character sequence of BACKSLASH (ASCII decimal 92), followed by a Dawson/Stenerson 31 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 LATIN SMALL LETTER N (ASCII decimal 110) or a LATIN CAPITAL LETTER N (ASCII decimal 78), that is "\n" or "\N". The "TEXT" property values may also contain special characters that are used to signify delimiters, such as a COMMA character for lists of values or a SEMICOLON character for structured values. In order to support the inclusion of these special characters in "TEXT" property values, they need to be escaped with a BACKSLASH character. A BACKSLASH character (ASCII decimal 92) in a "TEXT" property value MUST be escaped with another BACKSLASH character. A COMMA character in a "TEXT" property value MUST be escaped with a BACKSLASH character (ASCII decimal 92). A SEMICOLON character in a "TEXT" property value MUST be escaped with a BACKSLASH character (ASCII decimal 92). However, a COLON character in a "TEXT" property value SHALL NOT be escaped with a BACKSLASH character.Example: A multiple line value of: Project XYZ Final Review Conference Room - 3B Come Prepared. would be represented as: Project XYZ Final Review\n Conference Room - 3B\nCome Prepared. 4.3.12 Time Value Name: TIME Purpose: This value type is used to identify values that contain a time of day. Formal Definition: The data type is defined by the following notation: time = time-value *("," [WSP] time-value) time-value = time-hour time-minute time-second [time-utc] time-hour = 2DIGIT ;00-23 time-minute = 2DIGIT ;00-59 time-second = 2DIGIT ;00-60 ;The "60" value is used to account for years with "leap" seconds. time-utc = "Z" Description: If the property permits, multiple "time" values MAY be specified using a COMMA character (ASCII decimal 44) separator character. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. The "TIME" data type is used to identify values that contain a time of day. The format is based on the [ISO 8601] complete Dawson/Stenerson 32 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 representation, basic format for a time of day. The text format consists of a two-digit 24-hour of the day (i.e., values 0-23), two- digit minute in the hour (i.e., values 0-59), and two-digit seconds in the minute (i.e., values 0-59). Fractions of a second are not supported by this format. In parallel to the "DATE-TIME" definition above, the "TIME" data type expresses time values in three forms: Note: The form of time with UTC offset MUST NOT be used. For example, the following is NOT VALID for a time value: 230000-0800 FORM #1 LOCAL TIME The local time form is simply a time value that does not contain the UTC designator nor does it reference a time zone. For example, 11 PM: 230000 Time values of this type are said to be "floating" and are not bound to any time zone in particular. They are used to represent the same hour, minute, and second value regardless of which time zone is currently being observed. For example, an event MAY be defined that indicates that an individual will be busy from 11:00 AM to 1:00 PM every day, no matter which timezone the person is in. In these cases, a local time MAY be specified. The recipient of an iCalendar object with a property value consisting of a local time, without any relative time zone information, should interpret the value as being fixed to whatever timezone the ATTENDEE is in at any given moment. This means that two ATTENDEEs may participate in the same event at different UTC times; floating time should only be used where that is reasonable behavior. In most cases, a fixed time is desired. To properly communicate a fixed time in a property value, either UTC time or local time with time zone reference MUST be specified. The use of local time in a TIME value without the TZID property parameter is to be interpreted as a local time value, regardless of the existence of "VTIMEZONE" calendar components in the iCalendar object. FORM #2: DATE WITH UTC TIME UTC time, or absolute time, is identified by a LATIN CAPITAL LETTER Z suffix character (ASCII decimal 90), the UTC designator, appended to the time value. For example, the following represents 0700 UTC: 070000Z The TZID property parameter MUST NOT be applied to TIME properties whose time values are specified in UTC. Dawson/Stenerson 33 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE The local time with reference to time zone information form is identified by the use the TZID property parameter to reference the appropriate time zone definition. TZID is discussed in detail in the section on Time Zone. Example: The following represents 8:30 AM in New York, five hours behind UTC, in each of the three formats using the "DTSTART" property: DTSTART:19980312T083000 DTSTART:19980312T133000Z DTSTART;TZID=America-New York:19980312T083000 4.3.13 URI Value Name: URI Purpose: This value type is used to identify values that contain a uniform resource identifier (URI) type of reference to the property value. Formal Definition: The data type is defined by the following notation: uri = Description: This data type might be used to reference binary information, for values that are large, or otherwise undesirable to include directly in the iCalendar object. The URI value formats in RFC 1738, RFC 2111 and any other IETF registered value format MAY be specified. Any IANA registered URI format MAY be used. These include, but are not limited to, those defined in RFC 1738 and RFC 2111. When a property parameter value is a URI value type, the URI must be specified as a quoted-string value. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: The following is a URI for a network file: http://host1.com/my-report.txt 4.3.14 UTC Offset Value Name: UTC-OFFSET Dawson/Stenerson 34 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Purpose: This value type is used to identify properties that contain an offset from UTC to local time. Formal Definition: The data type is defined by the following notation: utc-offset = time-numzone ;As defined above in time data type Description: The PLUS SIGN character MUST be specified for positive UTC offsets. No additional content value encoding (i.e., BACKSLASH character encoding) is defined for this value type. Example: The following are UTC offsets are given for standard time for New York (five hours behind UTC) and Geneva (one hour ahead of UTC): -0500 +0100 4.4 iCalendar Object 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 MAY 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 = "BEGIN" ":" [WSP] "VCALENDAR" CRLF icalbody "END" ":" [WSP] "VCALENDAR" CRLF [icalobject] 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:19970715T045959Z SUMMARY:Bastille Day Party END:VEVENT END:VCALENDAR Dawson/Stenerson 35 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 4.5 Property A property is the definition of an individual attribute describing a calendar property 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 places no imposed ordering of properties within an iCalendar object. Property names, parameter names and parameter values (i.e., everything to the left of the ":" on a line) are case insensitive. For example, the property name "DUE" is the same as "due" and "Due". 4.6 Calendar Components The body of the iCalendar object consists of a sequence of calendar properties and one or more calendar components. The calendar properties are attributes that apply to the calendar as a whole. The calendar components are collections of properties that express a particular calendar semantic. For example, the calendar component MAY specify an event, a to-do, a journal entry, time zone information, or free/busy time information, or an alarm. The body of the iCalenar object is defined by the following notation: icalbody = calprops 1*component calprops = [calscale] [method] prodid version component = 1*(eventc / todoc / journalc / freebusyc / / timezonec / x-name / iana-token) 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. 4.6.1 Event Component Component Name: "VEVENT" Purpose: Provide a grouping of component properties that describe an event. Dawson/Stenerson 36 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Format Definition: A "VEVENT" calendar component is defined by the following notation: eventc = "BEGIN" ":" [WSP] "VEVENT" CRLF eventprop *alarmc "END" ":" [WSP] "VEVENT" CRLF eventprop = *attach *attendee *categories [class] *comment *contact [created] [description] [dtend / duration] dtstart *exdate *exrule [geo] [last-mod] [location] [organizer] [priority] [rstatus] *related *resources *rdate *rrule dtstamp [seq] [status] summary [transp] uid [url] [recurid] Description: A "VEVENT" calendar component is a grouping of component properties and an OPTIONAL "VALARM" calendar component that represent a scheduled amount of time on a calendar. For example, it MAY be an activity; such as a one-hour, department meeting from 8:00 AM to 9:00 AM, tomorrow. Generally, these events 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 MAY have its Time Transparency set to "TRANSPARENT" in order to prevent blocking of the event in searches for busy time. The "VEVENT" is also the calendar component used to specify an anniversary or daily reminder within a calendar. These events have a DATE value type for the "DTSTART" and "DTEND" properties instead of the default data type of DATE-TIME. If such a "VEVENT" has an end time, it MUST be specified as a DATE value also. The anniversary type of "VEVENT" MAY 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 MUST include the "DTSTAMP", "DTSTART", "SUMMARY" and "UID" properties. In addition, it MUST include the "SEQUENCE" property, if it's value is greater than zero. The "VEVENT" calendar component cannot be nested within another calendar component. The "VEVENT" calendar components MAY be related to each other or to a "VTODO" or "VJOURNAL" calendar component with the "RELATED-TO" property. Dawson/Stenerson 37 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Example: 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 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 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 4.6.2 To-do Component Component Name: VTODO Purpose: Provide a grouping of calendar properties that describe a to-do. Formal Definition: A "VTODO" calendar component is defined by the following notation: Dawson/Stenerson 38 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 todoc = "BEGIN" ":" [WSP] "VTODO" CRLF todoprop *alarmc "END" ":" [WSP] "VTODO" CRLF todoprop = *attach *attendee *categories [class] *comment [completed] *contact [created] [description] dtstamp [dtstart] [due / duration] *exdate *exrule [geo] [last-mod] [location] [organizer] [percent] priority [rstatus] *related *resources *rdate *rrule [recurid] [seq] [status] summary uid [url] Description: A "VTODO" calendar component is a grouping of component properties and an OPTIONAL "VALARM" calendar component that represent an action-item or assignment. For example, it MAY be an item of work assigned to an individual; such as "turn in travel expense today". The "VTODO" calendar component MUST include the "DTSTAMP", "PRIORITY", "SUMMARY" and "UID" properties. In addition, it MUST include the "SEQUENCE" property, if it's value is greater than zero. The "VTODO" calendar component cannot be nested within another calendar component. If "VTODO" calendar components need to be related to each other or to a "VTODO" or "VJOURNAL" calendar component, they can specify a relationship with the "RELATED-TO" property. A "VTODO" calendar component without the "DTSTART" and "DUE" (or "DURATION") properties specifies a to-do that is associated with each successive calendar dates, until it is completed. 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:VEVENT 4.6.3 Journal Component Component Name: VJOURNAL Purpose: Provide a grouping of component properties that describe a journal entry. Formal Definition: A "VJOURNAL" calendar component is defined by the following notation: Dawson/Stenerson 39 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 journalc = "BEGIN" ":" [WSP] "VJOURNAL" CRLF jourprop "END" ":" [WSP] "VJOURNAL" CRLF jourprop = *attach *attendee *categories [class] *comment *contact [created] description dtstart dtstamp *exdate *exrule [last-mod] [organizer] [recurid] *related *rdate *rrule [rstatus] [seq] summary uid [url] Description: A "VJOURNAL" calendar component is a grouping of component properties that represent one or more descriptive text notes on 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 MAY 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 MUST include the "DTSTAMP", "DTSTART", "DESCRIPTION", "SUMMARY" an "UID" properties. In addition, it MUST include the "SEQUENCE" property, if it's value is greater than zero. The "VJOURNAL" calendar component cannot be nested within another calendar component. If "VJOURNAL" calendar components need to be related to each other or to a "VEVENT" or "VTODO" calendar component, they can specify a relationship 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. 2. Telephone Conference: ABC Corp. sales representative called to discuss new printer. Promised to get us a demo by Friday. 3. Henry Miller (Handsoff Insurance): Car was totaled by tree. Is looking into a loaner car. 654-2323 (tel). END:VJOURNAL Dawson/Stenerson 40 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 4.6.4 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. Formal Definition: A "VFREEBUSY" calendar component is defined by the following notation: freebusyc = "BEGIN" ":" [WSP] "VFREEBUSY" CRLF fbprop "END" ":" [WSP] "VFREEBUSY" CRLF fbprop = fbrequest / fbreply / busytime fbrequest = 1*attendee dtstart dtend [duration] *comment dtstamp [last-mod] [seq] uid ;This set of properties is used for free/busy time request. fbreply = 1*attendee [created] *comment [dtstart dtend] dtstamp 1*freebusy [last-mod] [rstatus] [seq] uid [url] ;This set of properties is used for free/busy time reply. busytime = attendee dtstamp dtstart dtend *comment 1*freebusy [url] 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 "VFREEBUSY" calendar component MUST include the "ATTENDEE", "DTSTAMP", "DTSTART", "DTEND", and "UID" properties. In addition, it MUST include the "SEQUENCE" property, if it's value is greater than zero. When used to reply to a request for free/busy time, the "VFREEBUSY" calendar component MUST include the "ATTENDEE", "DTSTAMP", "FREEBUSY", and "UID" properties. In addition, it MUST include the "SEQUENCE" property, if it's value is greater than zero. When used to publish busy time, the "VFREEBUSY" calendar component MUST include the "ATTENDEE", "DTSTAMP", "DTSTART", "DTEND", "FREEBUSY" properties. The "VFREEBUSY" calendar component cannot be nested within another calendar component. Multiple "VFREEBUSY" calendar components MAY 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. Dawson/Stenerson 41 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 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 can be expressed using the "FREEBBUSY" property. This property provides a terse representation of time periods. One or more "FREEBUSY" properties MAY be specified in the "VFREEBUSY" calendar component to describe the Free/Busy information. 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 MAY be used in combination with the "DURATION" property to express a request for a duration of free time within a given 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: 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 SEQUENCE:0 UID:19970901T0830000-uid1@host1.com END:VFREEBUSY The following is an example of a "VFREEBUSY" calendar component used to reply to the request with busy time information: BEGIN:VFREEBUSY ATTENDEE:MAILTO:john_public@host2.com DTSTAMP:19970901T100000Z SEQUENCE:0 UID:19970901T0830000-uid1@host1.com FREEBUSY;VALUE=PERIOD:19971015T050000Z/PT8H30M, 19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M URL:http://host2.com/pub/busy/jpublic-01.vcs COMMENT:This iCalendar file contains busy time information for the next three months. END:VFREEBUSY The following is an example of a "VFREEBUSY" calendar component used to published busy time information. BEGIN:VFREEBUSY ATTENDEE:jsmith@host.com DTSTART:19980313T141711Z Dawson/Stenerson 42 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 DTEND:19980410T141711Z FREEBUSY:19980314T233000Z/19980315T003000Z FREEBUSY:19980316T153000Z/19980316T163000Z FREEBUSY:19980318T030000Z/19980318T040000Z URL:http://www.host.com/calendar/busytime/jsmith.ifb END:VFREEBUSY 4.6.5 Timezone 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" ":" [WSP] "VTIMEZONE" CRLF tzid [last-mod] [tzurl] 1*(standardc / daylightc) "END" ":" [WSP] "VTIMEZONE" CRLF standardc = "BEGIN" ":" [WSP] "STANDARD" CRLF tzprop "END" ":" [WSP] "STANDARD" CRLF daylightc = "BEGIN" ":" [WSP] "DAYLIGHT" CRLF tzprop "END" ":" [WSP] "DAYLIGHT" CRLF tzprop = *comment dtstart [rdate / rrule] *tzname tzoffsetto tzoffsetfrom 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 for the eastern United States starting from 1967. Each line represents a description or rule for a particular observance. Effective Observance Rule Dawson/Stenerson 43 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Date (Date/Time) Offset Abbreviation 1967-* lastSun 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 Interoperability between two calendaring and scheduling applications, especially for recurring events, to-dos or journal entries, is dependent on the ability to capture and convey date and time information in an unambiguous format. The specification of current time zone information is integral to this behavior. If present, the "VTIMEZONE" calendar component defines the set of Standard Time and Daylight Saving Time observances (or rules) for a particular time zone for a given interval of time. The "VTIMEZONE" calendar component cannot be nested within other calendar components. Multiple "VTIMEZONE" calendar components MAY 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 the section "4.1.10.11 Time" for proper interpretation of floating time). It MAY 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. 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 Dawson/Stenerson 44 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 - the last onset date-time for the observance, if a last onset is known. - the offset to be applied for the observance - a rule that describes the day and time when the observance takes effect - an optional name for the observance For a given time zone, there may be multiple unique definitions of the observances over a period of time. Each observance is described using either a "STANDARD" or "DAYLIGHT" sub-component. The collection of these sub-components is used to describe the time zone for a given period of time. The offset to apply at any given time is found by locating the observance that has the last onset date and time before the time in question, and using the offset value from that observance. The top-level properties in a "VTIMEZONE" calendar component are: The mandatory "TZID" property is a text value that uniquely identifies the 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. 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 1967 for the eastern United States: DTSTART:19671029T020000 TZOFFSETFROM:-0400 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. Dawson/Stenerson 45 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 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 are 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: - 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 as a full DATE-TIME value, using local time plus the UTC offset. - The local time and UTC offset values provided in the "DTSTART" property for the given observance MUST be used when generating the onset date-time values (instances) from the RRULE. This interpretation of the "DTSTART" UTC offset value is specific to "RRULE" usage in the "VTIMEZONE" specification. Alternatively, the "RDATE" property MAY 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 with UTC offset. The optional "COMMENT" property is also allowed for descriptive explanatory text. Example: The following are examples of the "VTIMEZONE" calendar component: This is a simple example showing 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 02:00:00 EST (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-9am, starting June 1, 1997, ending December 31, 1997. BEGIN:VTIMEZONE TZID:America-New_York LAST-MODIFIED:19870101T000000Z BEGIN:STANDARD DTSTART:19971026T020000 RDATE:19971026T020000 Dawson/Stenerson 46 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 TZNAME:EST END:STANDARD BEGIN:DAYLIGHT DTSTART:19971026T020000 RDATE:19970406T020000 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT END:VTIMEZONE This is a simple example showing the 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 on into the known future. BEGIN:VTIMEZONE TZID:America-New_York LAST-MODIFIED:19870101T000000Z TZURL:http://zones.stds_r_us.net/tz/America-New_York 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 This is an example showing 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:America-New_York LAST-MODIFIED:19870101T000000Z BEGIN:STANDARD DTSTART:19671029T020000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 TZNAME:EST END:STANDARD BEGIN:DAYLIGHT Dawson/Stenerson 47 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 DTSTART:19870405T020000 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT END:VTIMEZONE This is an example showing 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:America-New_York 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=19980404T070000 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 4.6.6 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" ":" [WSP] "VALARM" CRLF (audioprop / dispprop / emailprop / procprop) "END" ":" [WSP] "VALARM" CRLF Dawson/Stenerson 48 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 audioprop = alarmtype trigger [duration repeat] attach dispprop = alarmtype description trigger [duration repeat] emailprop = alarmtype 1*attendee *attach description trigger [duration repeat] summary procprop = alarmtype attach [description] trigger [duration repeat] 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 "ALARM-TYPE" and "TRIGGER" properties. In addition, an AUDIO type of alarm MUST include the "ATTACH" property to point to a digital sound resource to be played. The DISPLAY type of alarm MUST include the "DESCRIPTION" property. The EMAIL type of alarm MUST include the "ATTENDEE", "DESCRIPTION" and "SUMMARY" properties. The PROCEDURE type of alarm MUST include the "ATTACH" property to point to a procedure resource to be invoked. The "VALARM" calendar component MUST only appear within either a "VEVENT" or "VTODO" calendar component. The "VALARM" calendar components cannot be nested. Multiple "VALARM" calendar components MAY be specified. 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 MAY alternately be set to an absolute calendar 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, the "DTEND" or "DTSTART" and "DURATION" properties MUST be present. In an alarm in a "VTODO" calendar component set to trigger on the "END" of the to-do, the "DUE" or "DTSTART" and "DURATION" properties MUST be present. The alarm MAY be defined such that it triggers repetitively. 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 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 Dawson/Stenerson 49 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 are absent, then the alarm will not repeat beyond the initial trigger. The "ALARM-TYPE" property is used within the "VALARM" calendar component to specify the type of the alarm. The "ALARM-TYPE" property value of AUDIO specifies an alarm that triggers with an audio sound; a value of DISPLAY specifies an alarm that triggers with the "Calendar User Agent" displaying text; the value of EMAIL specifies an alarm that triggers the posting of an electronic email message to one or more email addresses; and the value of PROCEDURE specifies an alarm that triggers the execution of a procedure. The "ALARM-TYPE" property MUST specify just one of these valid values. Multiple categories of alarms MAY BE specified by defining more than one, different categories of "VALARM" calendar components within a "VEVENT" or "VTODO" calendar component. In an AUDIO type of alarm, the "ATTACH" property in the "VALARM" calendar component MUST specify an audio sound file that is intended to be rendered as the alarm effect. If an "ATTACH" property is specified that does not refer to a digital sound resource, then no audio alarm will be sounded. If the digital sound resource is in a format that cannot be rendered, then no audio alarm will be sounded. In a DISPLAY type of alarm, the "DESCRIPTION" property in the "VALARM" calendar component is intended to be displayed as the alarm effect. In an EMAIL category of alarm, the intended alarm effect is to use the "DESCRIPTION" property in the "VALARM" calendar component as the body text of an email message that is to be sent to the addresses specified by any "ATTENDEE" properties present in the "VALARM" calendar component. The "SUMMARY" property in the "VALARM" calendar component is intended to be used as the subject text for the email. Any "ATTACH" properties are sent as email attachments. In a PROCEDURE type of 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, should 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: The following example is for a "VALARM" calendar component that specifies an audio alarm that will sound at a precise time and repeat 4 more times at 15 minute intervals: BEGIN:VALARM TRIGGER;VALUE=DATE-TIME:19970317T133000Z REPEAT:4 DURATION:PT15M ALARM-TYPE: AUDIO Dawson/Stenerson 50 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 ATTACH:ftp://host.com/pub/sounds/bell-01.wav END:VALARM The following example is for a "VALARM" calendar component that specifies a display alarm that will trigger 15 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 ALARM-TYPE:DISPLAY DESCRIPTION:Breakfast meeting with executive\n team at 8:30 AM EST. END:VALARM The following example is for a "VALARM" calendar component that specifies an email alarm that will trigger 2 days before the scheduled due date/time of a to-do it is associated with. It does not repeat. The email has a subject, body and attachment link. BEGIN:VALARM TRIGGER:P2D ALARM-TYPE: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:http://host.com/templates/agenda.doc END:VALARM The following example is for 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 ALARM-TYPE:PROCEDURE ATTACH:ftp://host.com/novo-procs/felizano.exe END:VALARM 4.7 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. Dawson/Stenerson 51 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 4.7.1 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 Conformance: Property MAY 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. No property parameters MAY be specified on this property. Format Definition: The property is defined by the following notation: calscale = "CALSCALE" ":" [WSP] calvalue CRLF calvalue = "GREGORIAN" / iana-token Example: The following is an example of this property: CALSCALE:GREGORIAN 4.7.2 Method Property Name: METHOD Purpose: This property defines the iCalendar object method associated with the calendar object. Value Type: TEXT Conformance: The property MAY 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]. Dawson/Stenerson 52 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 If this property is not present in the iCalendar object, then no scheduling transaction MAY 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. No property parameters MAY be specified on this property. Format Definition: The property is defined by the following notation: method = "METHOD" ":" [WSP] method-value CRLF method-value = 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 4.7.3 Product Identifier Property Name: PRODID Purpose: This property specifies the identifier for the product that created the iCalendar object. Value Type: TEXT Conformance: The property MUST be specified in an iCalendar object but can only appear once. Description: The vendor of the implementation should assure that this is a globally unique identifier; using some technique such as an ISO 9070 FPI value. 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. No property parameters MAY be specified on this property. Format Definition: The property is defined by the following notation: prodid = "PRODID" ":" [WSP] pidvalue CRLF pidvalue = text ;Any text that describes the product and version ;and that is generally assured of being unique. Example: The following is an example of this property: PRODID:-//ABC Corporation//NONSGML My Product//EN Dawson/Stenerson 53 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 4.7.4 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 Conformance: This property MUST be specified by in an iCalendar object, but MAY only be specified once. Description: A value of "2.0" corresponds to this memo. No property parameters MAY be specified on this property. Format Definition: The property is defined by the following notation: version = "VERSION" ":" [WSP] vervalue CRLF vervalue = "2.0" ;This memo / maxver / (minver ";" [WSP] maxver) minver = ;Minimum iCalendar version used to create the iCalendar object maxver = ;Maximum iCalendar version used to create the iCalendar object Example: The following is an example of this property: VERSION:2.0 4.8 Component Properties The following properties MAY appear within calendar components, as specified by each component property definition. 4.8.1 Descriptive Component Properties The following properties specify descriptive information about calendar components. 4.8.1.1 Attachment Property Name: ATTACH Purpose: The property provides the capability to associate a document object with a calendar component. Dawson/Stenerson 54 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 Value Type: The default value type for this property is URI. The value type MAY also be reset to BINARY in order to include inline binary encoded content information. Conformance: The property MAY be specified in an iCalendar object. Description: The property MAY only be specified within "VEVENT", "VTODO", "VJOURNAL", or "VALARM" calendar components. This property MAY be specified multiple times within an iCalendar object. Only the "ENCODING" and "VALUE", property parameters MAY be specified on this property. Format Definition: The property is defined by the following notation: attach = ("ATTACH" ":" [WSP] uri CRLF) attach =/ ("ATTACH" ";" [WSP] "ENCODING" "=" "b" ";" [WSP] "VALUE" "=" "text" ":" [WSP] binary Example: The following are examples of this property: ATTACH:CID:jsmith.part3.960817T083000.xyzMail@host1.com ATTACH:FTP://xyzCorp.com/pub/reports/r-960812.ps 4.8.1.2 Categories Property Name: CATEGORIES Purpose: This property defines the categories for a calendar component. Value Type: TEXT Conformance: The property MAY only 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 MAY be specified as a list of categories separated by the COMMA character (ASCII decimal 44). Only the "LANGUAGE" property parameters MAY be specified on this property. Format Definition: The property is defined by the following notation: categories = "CATEGORIES" [catparam] ":" [WSP] catvalue CRLF catparam = ";" [WSP] languageparm Dawson/Stenerson 55 Expires September 1998 Internet Draft C&S Core Object Specification March 6, 1998 catvalue = "ANNIVERSARY" / "APPOINTMENT" / "BUSINESS" / "EDUCATION" / "HOLIDAY" / "MEETING" / "MISCELLANEOUS" / "NON-WORKING HOURS" / "NOT IN OFFICE" / "PERSONAL" / "PHONE CALL" / "SICK DAY" / "SPECIAL OCCASION" / "TRAVEL" / "VACATION" / text ;These are just examples ;Used only in "VEVENT", "VTODO" and "VJOURNAL" calendar components. Example: The following are examples of this property: CATEGORIES:APPOINTMENT,EDUCATION CATEGORIES:MEETING 4.8.1.3 Classification Property Name: CLASS Purpose: This property defines the access classification for a calendar component. Value Type: TEXT Conformance: The property MAY only be specified in a "VEVENT", "VTODO" or "VJOURNAL" calendar components. The property MAY only be specified once. 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 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. The [ICMS] provides a broader description of the security system within a calendar application. No property parameters MAY be specified on this property. Format Definition: The property is defined by the following notation: class = "CLASS" ":" [WSP] classvalue CRLF classvalue = "PUBLIC" / "PRIVATE" / "CONFIDENTIAL" / iana-token / x-name ;Default is PUBLIC Dawson/Stenerson 56