144. The representative of the United States of America, on behalf of the Chair of IWG on EVS UN GTR No. 13, Phase 2 and of GRSP, informed AC.3 on the progress of the group. She reported on IWG meeting that had been held from 6 to 9 November 2019, in Stuttgart, Germany. She stated that, under Phase 2 of the UN GTR, the task forces and subgroups of IWG were working on issues such as extending the scope of the UN GTR to cover heavy-duty vehicles and buses, material compatibility, tank stress rupture, fire test parameters and further clarification of existing GTR test procedures. Overall, she added that IWG was on track, however, some items had proven to be more complex and challenging, and additional work may be necessary. She added, that task force work would continue on heavy duty vehicles and buses, fuelling receptacle requirements, fire tests and test procedure recommendations. In addition, subgroups were looking at issues such as initial burst pressure, material compatibility and humid gas stress corrosion cracking.