What is the purpose of the 'Wishlist purchase' field ?

Problem/Motivation

I'm trying to implement commerce_wishlist in an existing Commerce website. Unfortunately there isn't a lot of documentation about that. Figured out how to add the «Add to your wishlist» button next to the «Add to cart» button and how to add fields and «Add to cart» button in the user wishlist (using Views).

Now wondering what is the purpose or a common use case for using the «Wishlist purchase» field ?