Hi. I posted a message to a NeXT programmers newsgroup to find out where sigset_t is defined. This is one of the replies I got. I didnt have the time to try it yet, though... > Not sure it's a bug or just a difference between System V and >BSD systems. It's in <sys/signal.h> on NEXTSTEP 3.3. But to use >it, the -posix flag must be specified in CFLAGS. Andreas