INT 6F - 10NET - UNLOCK FCBsee File Control Block
	AH = 12h
	AL = mode
	    00h sequential
	    01h random
	    02h random block
		CX = number of records
	DS:DX -> FCBsee File Control Block (see #01345 at INT 21/AH=0Fh)
Return: CF clear if successful
	CF set on error
	    AX = error code (see also #03740)
		0002h file not found
SeeAlso: AH=11h