This International Standard specifies a method of determining whether an analytical system for natural gas is satisfactory, on the assumptions that a) the analytical requirements has been clearly and unambiguously defined, for the range and uncertainty of component concentration measurements, and the uncertainty of properties which may be calculated from these measurements; b) the analytical and calibration procedures have been fully described; c) the method is intended to be applied to gases having compositions which vary over ranges normally found in transmission and distribution networks.