With regard to the requirement of Paragraph 2.5.1.1.(e), the retrofit vehicle family relation applicable for the purpose of this Regulation only, will be considered valid for both indirect and direct injection petrol vehicles if all the following conditions are satisfied:● The retrofit system is "master-slave" according to the definition of Paragraph 2.1.5.● The retrofit system operates in indirect (port fuel) gas injection mode on direct petrol injection vehicles;● At least one petrol direct injection vehicle has been tested as parent vehicle as defined in Paragraph 2.5.