We've been having discussions at my company regarding when to apply a new gas analysis. We decided that a sample taken on 5/16/18 for a wellhead meter would be applied June 1, 2018. BUT if it's a sales category (sales, sales check) meter then we apply the gas analysis taken 5/16/18 on 5/1/2018, the same month the sample was taken. Are there any COPAS or ANSI rules that state what effective date to use? Is it up to the contracts for that lease?