For the demonstration of manual skill, this standard covers principles to be observed in the qualification of welder performance for the fusion welding of steels. Following uniform rules, the testing of skill according to this standard depends on welding process, joint type, materials, semi-finished products, filler metal, welding posiitions, kind of test pieces. Principles for uniform acceptance requirements for test pieces as well as formats for welder approval test certificate and manufacturer´s welding procedure specification are laid down.