How are the UV's for hair in content example/ character rendering set up

I’ve been looking at Unreals new hair rendering and trying to figure out how it all works with the hair material used in the Content Example for UE 4:11. I noticed each clump of hair cards has 3 UV’s: one with all 6 hair cards laid flat and 2 with only 1 laid flat. I know 1 of the UV’s is used for the lightmap (I believe it’s the 3rd) but not sure how the others are being used and how to set that up. Would like to bring in my own hard cards with the UV’s set up the same so I can use the Content Examples hair material as a starting point for my character hair.