cond Condition variable that the calling thread waits on. mutex Mutex associated with the condition variable specified in cond. abstime Absolute time at which the wait expires, if the condition has not been signaled or broadcast. See the pthread_get_expiration_np() routine, which is used to obtain a value for this argument. The abstime argument is specified in Universal Coordinated Time (UTC). In the UTC-based model, time is represented as seconds since the Epoch. The Epoch is defined as the time 0 hours, 0 minutes, 0 seconds, January 1st, 1970 UTC.