INT 2F - DOS 3.0+ ASSIGN - INSTALLATION CHECK                                   
	AX = 0600h
Return: AL = status
	    00h not installed
	    01h not installed, but not OK to install
	    FFh installed
Notes:	ASSIGN is not a TSR(Terminate and Stay Resident) A program which remains in memory after terminating in order to provide services to other programs or the user.  The name comes from the name of the DOS function call used to remain in memory after termination. in DR DOS 5.0; it is internally replaced by SUBST
	  (see INT 21/AH=52h)
	undocumentedInformation about a product which is not publicly available from the manufacturer, and must be determined by reverse-engineering (disassembly, trial-and-error, etc.).	 Undocumented information tends to change -- often dramatically -- between successive revisions of a product, since the manufacturer has no obligation to maintain compatibility in behavior which is not explicitly stated. prior to the release of DOS 5.0
SeeAlso: AX=0601h,INT 21/AH=52h