Int 7F Fn 41  - Alloy Ntnx - Lock File For User                            [N]

   AH = 41h
   AL = user ID
   DS:DX -> ASCIZ filename

Return: AL = status (see #3637)

Note:  requests exclusive read/write access to file

See Also: AH=00h,AH=41h"MW386",AH=42h"NTNX"

(Table 3637)
Values for Alloy function status:
 00h   successful
 01h   invalid function
 02h   already locked
 03h   unable to lock
 04h   lock table full or semaphore space exhausted