If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Return Description 0 Successful completion. [EINVAL] The value specified by cond is not a valid condition variable or the value specified by mutex is not a valid mutex, or Different mutexes are supplied for concurrent tis_cond_wait() operations on the same condition variable, or The mutex was not owned by the calling thread at the time of the call.