Library
From UMAWiki
Library objects are used to store all the assets used to generate the various UMAs in the scene.
A library is needed for each of the different asset types; slots, overlays, and races.
Luckily, there is already a prefab set up with all the library objects in it. Find the "UMA_DCS" prefab and drag it in to the scene to instantiate it. It is located at "UMA/Content/UMA/".
