INT 21 - DOS 4+ - EXTENDED OPEN/CREATE
AX = 6C00h
BL = open mode as in AL for normal open (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
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 exists
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 = 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
SeeAlso: AH=3Dh

See also: 213C

216C00 - DOS 4+ - EXTENDED OPEN/CREATE