This Recommendation applies to measuring systems for gaseous fuel: with a designed maximum flowrate Qmax equal to or greater than 100 m3/h at base conditions and for operating pressures equal to or greater than 200 kPa (2 bar) absolute; not fitted with diaphragm gas meters. It may apply to very large measuring systems located at the border between two countries as well as to smaller measuring systems, with the exception of measuring systems for compressed natural gas for vehicles (CNG). However, the provisions of this Recommendation may be adapted to other cases. This Recommendation lays down the metrological and technical requirements applicable to the measuring systems subject to legal metrology controls.