23. GRSP resumed discussion on limit values on the chest vertical acceleration of Q-dummies during the dynamic testing of ECRS, on the basis of GRSP-68-05 tabled by the expert from CLEPA. The expert from CLEPA introduced the proposal through a presentation (GRSP-68-10) showing GRSP that collection and analysis of data monitoring was progressing. He further encouraged Contracting Parties to the 1958 Agreement to provide data to support the analysis and the proposed limits. The expert from Spain introduced a presentation (GRSP-68-26), showing the test results conducted by her technical service on the effects of dummy type Q1.5 chin-thorax contact in measuring upper neck forces. GRSP noted that further data collection was needed and agreed to resume discussion on this topic at its May 2021 session.