Unaccounted- for Gas:
The difference between the total gas available from all sources, and the total gas accounted for as sales, net interchange, and company use. This difference includes leakage or actual losses, discrepancies due to meter inaccuracies, variations of temperature and/or pressure, and other variants, particularly due to measurements being made at different times.
This is the amount of natural gas you used during the billing period listed in MMBtus. This will be listed on your natural gas bill as MMBtus used.