iCalendar (RFC 5545)

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

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The use of calendaring and scheduling has grown considerably in the last decade. Enterprise and inter-enterprise business has become dependent on rapid scheduling of events and actions using this information technology. This memo is intended to progress the level of interoperability possible between dissimilar calendaring and scheduling applications. This memo defines a MIME content type for exchanging electronic calendaring and scheduling information. The Internet Calendaring and Scheduling Core Object Specification, or iCalendar, allows for the capture and exchange of information normally stored within a calendaring and scheduling application; such as a Personal Information Manager (PIM) or a Group-Scheduling product.

The iCalendar format is suitable as an exchange format between applications or systems. The format is defined in terms of a MIME content type. This will enable the object to be exchanged using several transports, including but not limited to SMTP, HTTP, a file system, desktop interactive protocols such as the use of a memory- based clipboard or drag/drop interactions, point-to-point asynchronous communication, wired-network transport, or some form of unwired transport such as infrared.

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 as 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 [2446bis].

The memo also includes a formal grammar for the content type based on the Internet ABNF defined in [RFC5234]. This ABNF is required for the implementation of parsers and to serve as the definitive reference when ambiguities or questions arise in interpreting the descriptive prose definition of the memo. Additional restrictions that could not easily be expressed with the ABNF syntax are specified as comments in the ABNF. Comments with normative statements should be treated as such.