Proposal to revise the definitions of REC devices and to introduce stricter limit values (reduction levels) for REC systems and transitional provisions for the sale of REC systems that meet the requirements of the REC Regulation in its original form. To assure coherence with the change in the definitions, the text also includes a revision of the test sequence for particulate reduction and the equivalence matrix for the Regulation No. 49 Standard series. The text was adopted by the Working Party on Pollution and Energy (GRPE) at its 68th session based on document GRPE/2014/4 as amended by GRPE-68-17-Rev.2.