https://github.com/zer0-os/zAuction/blob/master/contracts/Zauction.sol ZAuction enables an NFT owner to accept a bid for their NFT by submitting a message signed by the bidder, along with data that is verified to match what is recovered from the signature.
It also allows a user to modify the fee for the top level domain ID of the given NFT. What does this mean? Let's say a given subdomain
zero.cats.fluffy, this means that the top if the top level domain
zerohas an associated fee, that amount will be subtracted from that bid and sent to the owner of the top level domain. The fee that this domain has can be altered by the domain owner to values between 0$ and 10%, given 5 decimal places of precision. This means 1% is 100000, 5% is 500000, 7.89% is 789000, etc.
Because the zAuction contract deployment will create a change in the address, we have also added the ability to initialize the zAuction contract with a legacy address. This legacy address is the previous zAuction contract that allows any bids existing prior to the new deployment to not be lost and still accepted.