INT 21 - Phar Lap 386/DOS-Extender v4.1+ - MAP DATA FILE AT FILE OFFSET

	AX = 252Bh
	BH = 0Bh
	BL = subfunction
	    00h by linear address
		ECX = linear address at which to map data file
	    01h by logical address
		ES:ECX = logical address at which to map data file
	EDX = number of bytes to map
	DS:ESI -> mapping structure (see #01373)
	DS:EDI -> ASCIZ filename
Return: CF clear if successful
	CF set on error
	    EAX = error code
		0002h file error
		    ECX = phase (01h opening file, 02h seeking, 03h reading)
		    EDX = error code returned by DOS
		0009h invalid address
		0081h invalid parameters or 386|VMM not present
		0086h all 386|VMM file handles already in use
SeeAlso: AX=252Bh/BH=03h,AX=252Bh/BH=09h