All the Start_TeX macros call the server, freeing the caller as soon
as the request is accepted. The caller usually does not have to
wait until compilation finishes. This is only partially true. The
server can only handle one request at a time. If you queue several
requests while the server is busy, the Start_TeX macro and thus
the caller will have to wait till compilation of the previous
request finishes. Only MG is an exception to this rule, thanks to it's
amazingly well-thought ARexx interface! Nice job, Mike!