There are a number of things we have to check before we accept your order.

Firstly we check that you have not made a silly mistake in typing in the price. We don't want you to type in a purchase price which is so far above the market that everyone rushes to sell to you. Nor do we want you to type in a sale price which is so low that everyone rushes to buy from you. Both of these would be treated as errors and would cause your order to fail validation. By the way - these errors often arise because people put in a sensible price for one currency, but against another currency. So that is one to watch for.

Another check we do is that you have sufficient available resources to settle your deal. This means a seller must have the quantity of gold he wants to sell in the right vault before selling, and a buyer must have the quantity of money he is going to spend in the right currency before buying.