Orifice meters on one gas system, every error from a cited public figure or a labelled assumption. An explainer: it states no uncertainty for any real installation. The page that explains it
Measured receipts minus measured deliveries, as a share of true throughput, over one year of calibration intervals. The true gas balances exactly; every bit of imbalance here is measurement. Propagated by Monte Carlo after JCGM 101:2008, run until its 7.9.4 stopping rule is met.