Int 21 Fn 6C00  - DOS 4+ - Extended Open/create                            [D]

   AX = 6C00h
   BL = open mode as in AL for normal open (see INT 21/AH=3Dh)
       bit 7: inheritance
       bits 4-6: sharing mode
       bit 3 reserved
       bits 0-2: access mode
   BH = flags
       bit 6 = auto commit on every write (see also AH=68h)
       bit 5 = return error rather than doing INT 24h
   CX = create attribute
       bits 6-15 reserved
       bit 5: archive
       bit 4: reserved
       bit 3: volume label
       bit 2: system
       bit 1: hidden
       bit 0: readonly
   DL = action if file exists/does not exist
       bits 7-4 action if file does not exist
           0000 fail
           0001 create
       bits 3-0 action if file exists
           0000 fail
           0001 open
           0010 replace/open
   DH = 00h (reserved)
   DS:SI -> ASCIZ file name

Return: CF set on error
      AX = error code (see AH=59h)
   CF clear if successful
      AX = file handle
      CX = status
       1 file opened
       2 file created
       3 file replaced

Note:  the PC LAN Program only supports DL=01h, DL=10h/sharing=compatibility,
     and DL=12h

See Also: AH=3Ch,AH=3Dh,AX=6C01h