eglBeginCompositionMsft documentation

In the eglext.h file of the Colibri WEC 2013 SDK, there is a function declared as eglBeginCompositionMsft. Where can I find the documentation for this function?

Sorry, we don’t have any further documentation about that, this file comes from Microsoft without any additional documentation.

Do you have any contact at Microsoft from whom you may acquire this information?