anchor.diff:  	SET ENGINE_DOOM64EX=0
   	SET ENGINE_GZDOOM=0
   	SET ENGINE_ZANDRONUM=0
  -	SET "REQ=%~1"
   )
   REM # requires doom 64 capable engine; doom 64 ex only at this time
   IF /I "%~1" == "doom64" (
  
positive.code: 	SET ENGINE_CHOCODOOM=0
  	SET ENGINE_DOOM64EX=0
  	SET ENGINE_PRBOOM=0
  	SET "REQ=%~1"
  )
  REM # zandronum only:
  IF /I "%~1" == "zandronum" (
  
negative.code: 	SET ENGINE_DOOM64EX=0
  	SET ENGINE_PRBOOM=0
  	SET ENGINE_ZANDRONUM=0
  )
  IF /I "%~1" == "gzdoom-22" (
  	REM # disable all non-GZDoom engines
  