Once a trade has been registered, an open position is created. The open position has a series of rules:
Although clearing occurs at the open position level, trades are live until the expiry date.
Although trades with opposite sign on the same contract are normally netted (except in accounts, which have a "gross record”), the system does not delete the trades but keeps them registered.
This record is important for swap contracts.
In a future contract, where there is a daily variation margin, the contracts are fungible and since the variation margin updates all the prices of the contracts at the daily settlement price of the session, the netting of trades is complete. Nevertheless, this daily variation margin does not occur in swaps contracts, therefore the netting of trades is not as in futures, and a pending variation margin is maintained.