This International Standard specifies methods for the measurement and evaluation of gaseous and particulate exhaust emissions from heavy-duty engines under transient conditions on a test bed. The procedures it defines can be applied to any transient test cycle that does not require extreme system response times; it can therefore be used as an option to the regulated measurement equipment of certification test cycles — usually CVS-type systems — with the approval of the certification agency [among certification test cycles in place are the European transient cycle (ETC) and the US heavy-duty transient cycle (FTP)]. This International Standard is applicable to heavy-duty engines for commercial vehicles primarily designed for road use, but can also be applied to passenger car engines and to engines used for non-road applications. The test equipment specified in this International Standard can also be used in steady-state test cycles, however, if so, the calculation procedures will need to be replaced by those applicable to the particular test cycle.