This Publicly Available Specification mainly summarises the content of ISO/TR 14646[1] to assist the Informal Group on CRS of UNECE/GRSP in their development of a simplified side impact method based on commonly agreed input data. In addition to the content of ISO/TR 14646, new data and further recommendations have been included. Where not otherwise stated, ISO/TR 14646 is reference source. The essential input parameters given in Clause 3 are applicable to accessory child restraint systems aiming to offer side impact protection.