anchor.diff:  
   :req
   REM --------------------------------------------------------------------------------------------------------------------
  +REM # requires a limit-removing engine
  +IF /I "%~1" == "no-limit" (
  +	REM # disable Chocolate-* engines
  +	SET "ENGINE_CHOCODOOM=0"
  +	SET "REQ=%~1"
  +)
   REM # requires boom-compatible engine
   IF /I "%~1" == "boom" (
   	REM # disable non-boom engines
  
positive.code: IF /I "%~1" == "/PWAD" GOTO :pwad
  IF /I "%~1" == "/REQ"  GOTO :reqs
  
  REM # options:
  REM # warp to a level (will ask for difficulty)
  IF /I "%~1" == "/LEVEL" GOTO :level
  
  IF "%~1" == "--" GOTO :files
  
  IF "%~1" == "" GOTO :engine
  
  ECHO Invalid parameter!
  
negative.code: REM # [/REQ engines]    specify engine requirements,
  REM #                   can be any of the following:
  REM # 
  REM #			no-limit 	- requires a limits-removing engine
  REM #			boom		- requires boom-compatibility; prboom+ and above
  REM #                   prboom          - requires prboom+ specifically (either HW or SW); e.g. "Comatose.wad"
  REM #			sw		- requires a software renderer; choco-doom, prboom+, zdoom
  