A buyer who desires three iron at no more than five gold each orders:
> buy 79 3 5 Try to buy three iron  for 5 gold each.
Suppose the only seller of iron in this city had ordered:
> sell 79 5 6 Try to sell five iron  for 6 gold each.
The trade will not take place, because the seller's price exceeds the buyer's. Later, the buyer travels to a different city, where another seller has previously issued:
> sell 79 10 4 Try to sell ten iron  for 4 gold each.
As soon as the buyer enters the city, the trade will be matched:
Bought three iron  for 12 gold.
Note that the trade takes place at the seller's price, and that the seller will still be offering seven iron at four gold each.
If the seller had only one unit of iron for sale, the trade would have executed, but the buyer would still be looking for two more iron to buy, at five gold each or better.