xCal
xCal is an XML -compliant mapping of the iCalendar standard.
xCal is just a representation of iCalendar elements in XML and is not intended to be an alternative to or replace iCalendar . Rather, all elements, properties and parameters of iCalendar can be mapped in XML with xCal.
The definition of xCal is in the Internet Engineering Task Force in the version of August 2011 Internet standard RFC6321 . An earlier submission by other authors from 2005 expired in April 2006.
There is a simple XSLT script with which xCal data can be easily and completely translated into iCalendar.
Microformats.org defines with hcalendar a direct competition to xCal, but relies more on XHTML and related standards and, unlike xCal, does not endeavor to create an Internet standard.