BNR= buy and replace.
BNS= buy and stay
With both there is a board with items from the featured shops.
With a BNR anyone can come and buy from one of the featured shop. Once you make a purchase you post your transaction and then you (your shop) REPLACES the shop you just bought from.
With BNS it is done in rounds. Same concept, you come in and buy from one of the featured shops but instead of replacing them, you get a spot in the next round.
It is a great way to self promote..