anchor.diff:  REM # if this was DOOM or DOOM2, we could use FreeDOOM instead
   SET "FREEDOOM="
   REM # TODO: check these files exist too
  -IF /I "%SAVE_WAD%" == "DOOM"  SET "FREEDOOM=freedoom\freedoom1.wad"
  -IF /I "%SAVE_WAD%" == "DOOM2" SET "FREEDOOM=freedoom\freedoom2.wad"
  +IF /I "%IWAD%" == "DOOM.WAD"  SET "FREEDOOM=%IWADS%\freedoom\freedoom1.wad"
  +IF /I "%IWAD%" == "DOOM2.WAD" SET "FREEDOOM=%IWADS%\freedoom\freedoom2.wad"
   
   IF NOT "%FREEDOOM%" == "" (
   	ECHO:
  
positive.code: 	)
  )
  
  IF EXIST "%IWADS%\%IWAD%" (
  	REM # the IWAD exists as-is and requires no special provisions
  	SET PARAMS=%PARAMS% -iwad "%FIX_PATH%\%IWADS%\%IWAD%"
  	ECHO         -iwad : %IWADS%\%IWAD%
  	REM # skip ahead, no edge-cases to handle
  	GOTO :params
  )
  
  REM # IWAD is missing,
  REM # now search GOG / Steam for the IWAD:
  SET "IWAD_PATH="
  
  :iwad_doomu
  REM --------------------------------------------------------------------------------------------------------------------
  REM # are we looking for "The Ultimate DOOM"?
  IF /I NOT "%IWAD%" == "DOOM.WAD" GOTO :iwad_doom2
  
  REM # is Steam : The Ultimate DOOM installed?
  
negative.code: 	
  	REM # we keep %SAVE_WAD% as "DOOM" so that save games from
  	REM # shareware DOOM can be re-used in the full game
  	SET "IWAD_PATH=SHAREWARE\DOOM1.WAD"
  	
  	GOTO :iwad_found
  )
  