Flap - surplus auction (selling stablecoins for MKR) [contract]wards [usr: address] - rely/deny/auth Auth Mechanisms [uint]Bid - State of a specific Auction[Bid]bid - quantity being offered for the lot (MKR) [uint]lot - lot amount (DAI) [uint]guy - high bidder [address]tic - Bid expiry [uint48]end - when the auction will finish [uint48]bids (id: uint) - storage of all Bids by id [mapping]vat - storage of the Vat's address [address]ttl - bid lifetime / max bid duration (default: 3 hours) [uint48]lot - lot amount (DAI) [uint]beg - minimum bid increase (default: 5%) [uint]tau - maximum auction duration (default: 2 days) [uint48]kick - start an auction / put up a new DAI lot for auction [function]tend - make a bid, thus increasing the bid size / submit an MKR bid (increasing bid) [function]deal - claim a winning bid / settling a completed auction [function]gem - MKR Token [address]kicks - total auction count [uint]live - cage flag [uint]file - used by governance to set beg, ttl, and tau [function]yank - is used during Global Settlement to move tend phase auctions to the End by retrieving the collateral and repaying DAI to the highest bidder. [function]tick() - resets the end value if there has been 0 bids and the original end has passed.file:begttltauVow.bump which sets the Bid.lot for each Flap auction and the Vow.hump which determines the surplus buffer.auth - check whether an address can call this method [modifier function]rely - allow an address to call auth'ed methods [function]deny - disallow an address from calling auth'ed methods [function]Vow when the Vow has no system debt and has accumulated enough DAI to exceed the Surplus auction size (bump) plus the buffer (hump)​lot) of DAI is put up for sale. Bidders then complete for a fixed lot amount of DAI with increasing bid amounts of MKR. In other words, this means that bidders will keep placing MKR bid amounts in increments greater than the minimum bid increase amount that has been set (this is the beg in action).ttl) without another bid getting placed OR when auction duration (tau) has been reached. At auction end, the MKR received for the surplus DAI is then sent to be burnt thereby contracting the overall MKR supply.flip, flop, and flap).flap auction run the risk of overpaying MKR for the DAI as there is no upper limit to the bid size other than their MKR balance.tend, bid amounts will increase by a beg percentage with each new tend. The bidder must know the auction's id, specify the right amount of lot for the auction, bid at least beg % more than the last bid and must have a sufficient MKR balance.beg%] would get committed after the dishonest keeper's bid for the same, thereby preventing the honest keeper's bid from being accepted and forcing them to rebid with a higher price ((Past-bid + beg) + beg)). The dishonest keeper would need to pay higher gas fees to try to get a miner to put their transaction in first or collude with a miner to ensure their transaction is first. This could become especially important as the bid reaches the current market rate for MKR<>DAI.beg could be set to 3%, meaning if the current bidder has placed a bid of 1 MKR, then the next bid must be at least 1.03 MKR. Overall, the purpose of the bid increment system is to incentivize early bidding and make the auction process move quickly.kick's a new Flap Auction.bid above the initial 0 value set during the kick. Bidder 1's MKR balance is decreased and the Flap's balance is increased by the bid size. bid.guy is reset from the Vow address to Bidder 1's and bid.tic is reset to now + ttl.beg. Bidder 2's MKR balance is decreased and Bidder 1's balance is increased by Bidder 1's bid. The difference between Bidder 2's and Bidder 1's bid is sent from Bidder 2 to the Flap.bid by at least beg. Bidder 1's MKR balance is decreased and Bidder 2's MKR balance is increased by Bidder 2's bid. The amount Bidder 1 increased the bid is then sent from Bidder 1 to the Flap.bids, so they stop making bids. Once the Bid.tic expires, Bidder 1 calls deal and the surplus DAI tokens are sent to the winning bidder's address (Bidder 1) in the Vat and the system then burns the MKR received from the winning bidder. gem.burn(address(this), bids[id].bid).bump + hump is always auctioned off in bump increments. However, auctions run concurrently, so this would "flood the keeper market" and possibly result in too few bids being placed on any auction. This could happen through keepers not bidding on multiple auctions at once, which would result in network congestion because all keepers are trying to bid on all of the auctions. This could also lead to possible keeper collusion (if the capital pool is large enough, they may be more willing to work together to split it evenly at the system's expense).