INT 44 - Acorn BBC Master 512 - "OSARGS" - GET/SET FILE PARAMS FOR OPEN FILE

	AH = nonzero file handle
	AL = function
	    00h get sequential pointer for file
	    01h set sequential pointer for file
	    02h get length of file
	BX -> 4-byte data buffer
Return: BX buffer updated if appropriate
SeeAlso: INT 40"Acorn",INT 41"Acorn",INT 44/AH=00h,INT 45"Acorn",INT 4A"Acorn"