The Category element is an optional child element of the Categories element (section 22.214.171.124) that specifies a category that is assigned to the calendar item or exception item. It is defined as an element in the Calendar namespace.
The value of this element is a string data type, as specified in [MS-ASDTYPE] section 2.6.
A command request SHOULD include no more than 300 Category child elements per Categories element.
A command response SHOULD include no more than 300 Category child elements per Categories element.