The IETF has published the revision to iCalendar

RFC5545, Internet Calendaring and Scheduling Core Object Specification (iCalendar) has been published by the IETF as a Proposed Standard Protocol. This is the revision to RFC 2445 (iCalendar) which has been underway for some time. RFC5545 obsoletes RFC2445. See CalConnect congratulates everyone who was involved in progressing this work.