What is Coco.exe and Grammar.atg?

[AddioElectronics]

I noticed a bat file that runs coco.exe and uses Grammar.atg in the command.
The exe is not included in the repo, but I can still see it as a missing file in the project.

What is this for?

@"..\..\Coco\Coco.exe" -frames "..\..\Coco" Grammar.atg -namespace SA.CodeView.Parsing.TokenDefParsing
@IF %ERRORLEVEL% == 0 GOTO SUCCESS
:SUCCESS
:END
@del Parser.cs.old
@del Scanner.cs.old
@pause