An order book is typically used to match buyers and sellers. I can imagine an order book for the exchange contract family that would store exchange/order contract pointers and/or auction pointers. The order book would be a place where exchange opportunities could be discovered.
Some potential ideas for the order book:
The order book is a list of open exchange contracts; it should include all of the information necessary for a buyer to discover and interact with the order which may include all of the contract files (*.pdo) and all of the context files.
Listing an order may require that the seller include a deposit with the order book in order to ensure that those sellers continue to maintain the order book; that is, I can imagine that an order added to the order book would have a limited duration after which the deposit is forfeited to the order book. This is really about ensuring that information in the order book is not stale.
An order book is typically used to match buyers and sellers. I can imagine an order book for the exchange contract family that would store exchange/order contract pointers and/or auction pointers. The order book would be a place where exchange opportunities could be discovered.
Some potential ideas for the order book: