$MT or $MULTITHREADED directive
Purpose: The $MT and $MULTITHREADED directives specify that the COINIT_MULTITHREADED initialization option be used for the thread when the COM library is initialized for use by the calling thread.
$MT is currently only used to initialize the COM library in multithreaded mode by the BCX VBS_START function or the Emit_For_BCX_COM_StandardSet code emission for the BCX late binding COM interface. The $MT directive will be used later for multithread support in general.