INT 2F U - DOS 4+ XMA2EMS.SYS extension internal - INSTALLATION CHECK           
	AX = 1B00h
Return: AL = FFh if installed
Note:	XMA2EMS.SYS extension is only installed if DOS has page frames to hide.
	This extension hooks onto INT 67/AH=58h and returns from that call data
	  which excludes the physical pages being used by DOS.
SeeAlso: AH=1Bh"FRAME INFO"