The minimum amount of gas that may be traded on the OCM is 4,000 therms, so if a shipper's position is long or short by a volume less than 4,000 therms they may be forced simply to leave their balance to cash out.
The smallest quantity of gas that can be traded on the OCM is 4,000 therms. Therefore, if a shipper's position differs by less than 4,000 therms in either direction, they might have to close their position without trading any additional gas.