What are the xml trying to be loaded in LoadLayouts?

Guys, do you know in the Randomizer, when it reaches LoadParams() (https://github.com/thefifthmatt/SoulsRandomizers/blob/master/RandomizerCommon/GameData.cs#L223)  -> LoadLayouts() (https://github.com/thefifthmatt/SoulsRandomizers/blob/master/RandomizerCommon/GameData.cs#L1010) it tries to read some xml files from diste/Defs

What are those? Where do we take them from? 
