Extension and Customization of a Category Schema
Thanks to the XML representation, enhanced presence categories are extensible. They can be extended in the following ways:
An application developer can define a custom enhanced presence category to support application-specific presence features.
A category schema designer can extend an existing enhanced presence category to maintain version-related updates.
An application developer can extend an existing enhanced presence category to add custom presence features.
Enhanced presence extension and customization is available only to applications using Microsoft Unified Communications Managed API (UCMA) 3.0.