Opens a mutex semaphore.

#define INCL_DOSSEMAPHORES
#include <os2.h>

PSZ       pszName;  /*  A pointer to the ASCIIZ name of the semaphore to open. */
PHMTX     phmtx;    /*  Pointer to a mutex-semaphore handle. */
APIRET    ulrc;     /*  Return Code. */

ulrc = DosOpenMutexSem(pszName, phmtx);