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A standard for group calendaring and scheduling from the IETF. It enables calendaring data to be transmitted and automatically entered into the recipient's schedule. In addition a request for a meeting with free and busy times might be sent, and the recipient's software could book the time automatically and send back the response.

Proposed as a standard to replace proprietary specifications such as in Outlook/Exchange, IBM Notes and Groupwise, iCalendar messages are files with an .ical, .ics, .ifb or icalendar extension.

The IETF Calendaring and Scheduling Standards Simplification group, dubbed "calsify," works on interoperability between different scheduling systems.

The Successor to vCalendar
iCalendar superseded the vCalendar standard developed by Versit, then turned over to the Internet Mail Consortium (IMC) and later the IETF. It added more detail to vCalendar events and defined a protocol for transporting it.
References in periodicals archive ?
A free web services translates the hCalendar-formatted event listings used by Eventful into the iCalendar standard.
Lotus Organizer 5 incluye FoneSync para transferir contactos a la mayoria de telefonos celulares, administracion de contactos e iCalendar para programar citas por Internet con usuarios que usen distintos sistemas de correo.
Users of the mobile data service can now utilise the iCalendar feature to access and manage their calendars from their mobile phone.
The CommuniGate Pro platform works across multiple calendar standards, such as iCalendar, MAPI, WebCal, and now CalDAV for better interoperability of clients and organisational scheduling services.
Release 6 offers extended Internet functionality such as new HTML publishing features and support for the latest iCalendar, vCalendar and vCard standards.