INT 21 - MS-DOS 7.0+ - GENERIC IOCTL - GET LOCK FLAG STATE                      
	AX = 440Dh
	CX = 086Ch / 486Ch
	    (category code 08h for FAT12/16, 48h for FAT32; minor code 6Ch)
	BL = drive number (00h=default,01h=A:,etc)
Return: CF set on error
	    AX = error code (01h,02h,etc.) (see #01680 at AH=59h/BX=0000h)
	CF clear if successful
	    AX = access flag (see #01576)
SeeAlso: AX=440Dh"DOS 3.2+",AX=440Dh/CX=084Ah,AX=440Dh/CX=084Bh
SeeAlso: AX=440Dh/CX=0870h


(Table 01576)
Values for drive access flag:
 0000h	no writes/file mappings since last call
 0001h	write operation has occurred since last call
 0002h	file mapping has occurred since last call
Note:	function 6Ch resets the access flag every time it is called