21. In reply to the concerns raised by the Informal Working Group on the International Whole Vehicle Type Approval (IWG IWVTA) at the 175th session of WP.29 (ECE/TRANS/WP.29/1139, para. 67), the expert from the Russian Federation proposed to align the provisions of UN Regulation No. 117 related to approval numbers and markings with the provisions of Schedule 4 to the 1958 Agreement (GRB-68-19). The expert for ETRTO stated that he would contribute to the document. The Chair invited other experts to provide their comments to the expert of the Russian Federation with a view to producing an official document for consideration at the next session.