0                  Successful completion. The function executes
                       the semaphore lock operation.
    -1                 Indicates an error. The function sets errno to
                       one of the following values:

                       o  ETIMEDOUT - The semaphore could not
                          be locked before the specified timeout
                          expired.

                       o  EINVAL - The sem argument does not refer to
                          a valid semaphore. Or the process or thread
                          would have blocked, and the abs_timeout
                          parameter specified a nanoseconds field
                          value less than zero or greater than or
                          equal to 1000 million.

                       o  EVMSERR - OpenVMS specific nontranslatable
                          error code.