17. The Secretary of the IWG introduced ECE/TRANS/WP.29/GRRF/2016/29 (amended by GRRF-82-27) with technical requirements for coupling devices for the purpose of modular vehicle combinations as well as “in-use” requirements for the combination of vehicles. The proposal, supported by GRRF, received some comments about the possibility to verify, at the time of type approval, the compliance with these “in use” requirements. GRRF questioned whether a driver could be requested to verify during a coupling phase the compatibility requirements defined in the proposal. The expert from CLEPA showed that calculation tools were available on the website of his company (www.vbg.se) and argued that it would be possible. GRRF agreed that this aspect of the proposal would need further consideration by the IWG who should recognise that new measures must be enforceable via type approval.