Yes that is the normal setup with most contracts, 80% peliminary...

Yes that is the normal setup with most contracts, 80% peliminary payment and the balance later. If the price changes during the quotation period (QP) then the amount recieved will reflect that. In the last shipment CXO sent they had to pay the customer some money back instead of recieving something in the final payment because of falling prices during that period..when prices are rising the opposite happens...shipment specs also com into it, its just the way it works and averages out over time. Some payments will also fall into different quarters...

its probably why prices aren't mentioned in contracts but discovered later , it can be considered misleading giving a price when the final washup isn't known and will also change with each shipment ....

Cheers Whisky