Occasionally, after a process has started a NOWAIT I/O with
FREAD or FWRITE, something occurs that causes
completion of that I/O to be no longer needed.
Perhaps the process is "shutting down" and does not want to
wait for the I/O (that is, to issue IOWAIT or
IODONTWAIT).
MPE/iX lets
the process abort NOWAIT I/Os that have not yet completed by using
FCONTROL with a controlcode of
43. A condition code of CCE is returned if the
I/O was aborted; in this case, nothing more needs to be done.
CCG is returned if the I/O has already completed; in this case,
IODONTWAIT or IOWAIT must be called to clear it.
CCL and FSERR 79,
No NOWAIT I/O pending for special file, are returned if there was
nothing to abort.
