Patcher generates a alternative Setup.exe for Patch purposes.
Let's say, you have compressed a whole game, then after a while a DLC come out. To prevent compressing the whole game + dlc again, Patcher just compress DLC files which you can burn.
See Wiki page
Code:
[UpdateOptions]
-------------------------------------------------------------------------------------------------------------------------------------------
//UpdateName= // string
//UpdateNamePL= // string
//UpdateVersion= // string
//NeedGameVersion= // string
//NeedUpdateVersion= // string
If i'm not mistaken. Never used it.
BAMsE did it in the past with "Fallout 4" conversion.