This Feature will create new type of auctions, ONLY SWAP. Seller will place auction just for swapping, and buyers will not be able to bid on it or buy it, just offer swap, if seller will accept swap buyer will win the auction.
On part four of the listing process is where you would select the trade only aspect.
With this part of the auction a person will click on "make offer" link in auction details. You (the poster) then go to: Members Area>>Selling>>Items with Bids/Offers. Click on the link that states, "View offers" and either accept or refuse.