xcall MIAMEX, MX_CLRSIG, sigmask

(UNIX only) MX_CLRSIG allows you to clear specific bits in the signal received mask. This would be useful in a situation where you wanted to check whether a certain signal was received during a certain time frame. (First you would clear the bit for that signal, then later you would check, using MX_GETSIG, if the bit was set.)

sigmask (Signed Num) should be set to the sum of the signals from the table above (see MX_GETSIG) that you want cleared. Use –1 to clear all of the signal flags. 0 does nothing.

SUBMIT/W uses this function, along with function 54. First it clears the SIGCHLD signal flag (2), then submits the task, then sleeps, checking every second to see if the SIGCHLD signal flag has been set, which it will be when the submitted task terminates.