Amend para. 5.1.2. to change the number of samples from ten to eight, modify para. 5.1.3.1. to reduce samples from ten to eight and divide the other six samples into three groups instead of four by deleting the fourth group colour-fastness test requirement, add para. 5.1.7. specifying the chronological order of tests in tables for Classes IA, IB, IIIA, IIIB and Class IVA, and amend para. 3.5.3.1. to add provisions for verification of stability in time of optical properties and colour of retro-reflecting optical units of advance warning triangles in use and withdrawal of approval for systematic deficiencies.