I do not understand use of certain assets

I do not understand use of certain assets

I am currently studying FLARE mechanics, as I believe FLARE is a mature and usable isometric game engine. While looking at image assets in fantasycore mod, I see several spritesheets that I cannot understand, such as cloth_shirt.png, default_chest.png, default_feet.png and others within flare-game/mods/fantasycore/images/avatar/male/. My questions are:

1. Aren't spritesheets usually consists of full body: including armour, weapons and whatnots, in several degrees views to be used in game?
2. How are they used within the game?

I hope someone can enlighten me. Thank you beforehand.

Regards,
Dmitri.