INT 17 - Alloy NTNX,MW386 - SET TAB EXPANSION
AH = 9Ah
AL = mode
00h NTNX compatibility
DX = NTNX printer number (see AH=88h)
(FFFFh = current logical LPT1)
01h MW386
DX = MW386 printer number
CL = tab length (00h = no expansion, 01h-63h = spaces per tab)
Return: AL = status (see AH=81h)
Note:   beginning with MW386 v2.0, tab expansion is set on a per-printer basis
rather than a per-user basis; NTNX and MW386 v1.x ignore DX

See also: 17A4

179A - Alloy NTNX,MW386 - SET TAB EXPANSION