Many contracts (both sales and purchases) have a provision where the customer can deliver more than the contract quantity up to a point without penalty. The word overrun, in this context, will be the concept that allows a contract to be over-delivered. To allow for any contract overruns, go to Commodity accounting > Setup > Commodity accounting parameters > under Commodity set the “Allow overrun on sales contracts” and “Allow overrun on purchase contracts” toggles to yes if you want to allow on both contract types.