The gas line check is a natural static pressure check of the gas lines to indicate if there is a leak somewhere in the gas lines between the gas meter and home appliances. To do this, we check the meter first, and then we turn everything off that uses gas in the home including all pilots. After a period of time, we recheck the meter and look for any movement in the dial. If there is movement, that indicates there is a gas leak somewhere in the lines. It would be noted on the report as deficient.