EVMAIN is the heart of SNOMAN, for each event EVMAIN
executes one cycle of the main event loop. This could be a simple series of
processor calls as specified by a $processor_list command or a more
complicated event loop program (the programmable event loop is described in
section 9).
If you want even more control over the event loop then simply replace EVMAIN.
You are now free to call whatever processors you like in whatever order you
like, but should still use USER_DEFINE_TASK to request them. It is also
necessary to disable the processor sequence (whether it is
given by the variable cuser_pro_seq, an event loop program, or the JOBP
bank) because the processors given in the sequence would get initialised. This
can be achieved by setting the ignore_pro_seq flag in
USER_DEFINE_TASK. This has the additional effect of making the JOB bank
optional, although it is safer to provide it, unless replacing, or not using,
the software units that rely on it.
It should be noted that QNEXT calls EVMAIN a maximum number of times as specified by the event limit given in the JOB titles bank and, on return from EVMAIN, wipes the memory ready for the next event. If the concept of an event loop is not appropriate, then just treat EVMAIN as the top level execution routine and don't return at all. Instead, call ZEND when ready to terminate. One word of warning: ZTELL errors that force execution onto the ``next event '' will result in EVMAIN being called again. This can be detected by examining the variable NEV of the common /PCQNEX/ (see QNEXT).