INT 21 - Novell NetWare - SYNCHRONIZATION SERVICES - LOCK LOGICAL RECORD SET
        AH = D1h
        AL = lock type (00h exclusive, 01h shareable)
        if function C6h lock mode 00h:
            DL = mode
                00h no wait
                01h wait
        if function C6h lock mode 01h: (Novell only)
           BP = lock timeout in timer ticks (1/18 sec) 0000h = no wait
                0000h no wait
Return: AL = status (see AH=CBh)
Desc:   attempt to lock all logical record names listed in the log table
Notes:  this function is supported by NetWare 4.6+, Advanced Netware 1.0+,
          Banyan VINES, and Alloy NTNX
        status FFh will be returned if one or more logical records have been
          exclusively locked by another process
        locks on logical record names are advisory and may be ignored by other
          applications
SeeAlso: AH=CBh,AH=D0h,AH=D3h,AH=D5h