INT 2F - APPEND - INSTALLATION CHECK                                            
	AX = B700h
Return: AL = status
	    00h not installed
	    FFh installed
Note:	MS-DOS 3.30 APPEND refuses to install itself when run inside TopViewTopView, DESQview, TaskView, OmniView, other compatibles or
	  a TopView-compatible environment
SeeAlso: AX=B702h