If sigset() is used and disp is SIG_DFL, then the default action associated with that process will be taken when the signal occurs. If sigset() is used and disp is SIG_IGN, then the signal will be ignored signal occurs. If sigset() is used and disp is the address of a signal handler, then the signal handler will be executed when the signal is generated. If sigset( ) is used, and disp is the address of a signal handler, the system shall add sig to the calling process' signal mask before executing the signal handler The calling process's signal mask shall be restored to its state prior to the delivery of the signal, when the signal handler returns. If disp is equal to SIG_HOLD, sig shall be added to the calling process' signal mask. If disp is equal to SIG_HOLD, sig's disposition shall remain unchanged. If the signal had been blocked, upon successful completion, sigset( ) shall return SIG_HOLD If the signal had not been blocked, upon successful completion, sigset( ) shall return the signal's previous disposition If sigset() was not successful, SIG_ERR shall be returned and errno set to indicate the error.