XmMapSegmentEncoding searches the segment encoding registry for
an entry that matches the specified font list tag and returns a copy
of the associated compound text encoding format. The application is
responsible for freeing the storage associated with the returned data
by calling XtFree.
fontlist_tag
Specifies the compound string font list tag.
Return value
Returns a copy of the associated compound text encoding format
if the font list tag is found in the registry; otherwise, returns NULL.