(21)For engines adapted for marine use as propulsion engines, where the source engine is already type-approved in accordance with Directive 97/68/EC of the European Parliament and of the Council of 16 December 1997 on the approximation of the laws of the Member States relating to measures against the emission of gaseous and particulate pollutants from internal combustion engines to be installed in non-road mobile machinery 10 , or Regulation (EC) No 595/2009 of the European Parliament and of the Council of 18 June 2009 on type-approval of motor vehicles and engines with respect to emissions from heavy duty vehicles (euro VI) and on access to vehicle repair and maintenance information 11 , persons adapting engines should be able to rely on the proof of conformity issued by the original engine manufacturer where those adaptations have not altered the exhaust emission characteristics.