INT 2F U - DOS Navigator II - INSTALLATION CHECK                                
	AX = 9900h
Return: BX = 444Eh ('DN') if installed
	    AX = number of DOS Navigator executions
	    CL = child process exit code
	    DX = version number (see #02965)
Notes:	old versions of DOS Navigator II always returned AH=1, while newer
	  ones return AH=0 and store AL in the DN.FLG file
Program: DOS Navigator is a multi-window shell for MS-DOS by RIT S.R.L.
	  DOS Navigator™ is a registered trademark of RIT S.R.L.
SeeAlso: AX=9901h,AX=9902h,AX=9903h,AX=9904h,AX=9905h,AX=9906h


(Table 02965)
Values for DOS Navigator II version code:
 2100h	version 1.35
 2138h	version 1.38
 2141h	version 1.41
 2150h	version 1.50