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

                       o  EACCESS - Permission is denied to unlink
                          the named semaphore.

                       o  ENAMETOOLONG - The length of the path
                          name exceeds PSEM_MAX_PATHNAME defined
                          in semaphore.h.

                       o  ENOENT - The named semaphore does not
                          exist.

                       o  EVMSERR - OpenVMS specific nontranslatable
                          error code.