The function int pthread_mutexattr_destroy(pthread_mutexattr_t *attr) destroys a mutex attributes object; the object becomes, in effect, uninitialized. An implementation may cause pthread_mutexattr_destroy() to set the object referenced by 'attr' to an invalid value. *NOTE: What the last sentence states is implementation specific, thus it will not be covered. A destroyed 'attr' attributes object can be reinitialized using pthread_mutexattr_init(); the results of referencing an 'attr' object after it has been destroyed are undefined. If success, it returns 0. An error number may be returned if: [EINVAL] The value specified by 'attr' is invalid