INT 2F U - DOS 3.3+ internal - OPEN FILE                                        
	AX = 1226h
	CL = access mode
	DS:DX -> ASCIZA NUL-terminated ASCII string.	The ASCIZ string "ABC" consists of the four bytes 41h, 42h, 43h, and 00h.  Unless otherwise specified, maximum lengths given in the interrupt list do not include the terminating NUL. filename
	SS = DOS DS (must be using a DOS internal stack)
Return: CF set on error
	    AL = error code (see #01680 at INT 21/AH=59h/BX=0000h)
	CF clear if successful
	    AX = file handle
Notes:	can only be called from within DOS
	equivalent to INT 21/AH=3Dh
	used by NLSFUNC to access COUNTRY.SYS when invoked by the DOS kernel
SeeAlso: AX=1227h,INT 21/AH=3Dh