In general, the measuring systems that are covered by this Recommendation are intended for the refueling of motor vehicles, small boats, and aircraft with compressed natural gas, hydrogen, biogas, gas blends or other compressed gaseous fuels. They may also be applicable to other vehicles, for instance trains. Measuring systems for liquid petroleum gas are not included in the scope of this Recommendation. These are within the scope of OIML R 117, which covers fluids in a liquid state. In principle, this Recommendation applies to all measuring systems fitted with a meter as defined in 3.2.2 (continuous measurement), whatever the measuring principle may be of the meters or their application. This Recommendation is not intended to prevent the development of new technologies. According to the state of the art, this Recommendation is intended for measuring systems providing mass indications.