The current Chinese standard for gapless metal oxide surge arresters is issued as a recommended national standard, the form used in China for documents that a purchaser is expected to cite rather than one that the state enforces, and it replaced the compulsory designation under which the same requirement had previously been published. In Chinese procurement the standard is cited in the technical specification that accompanies a tender, so its status as a recommended standard does not make it optional in practice: a supplier to a utility or to a railway project will be held to it, and the type approval evidence assembled for the customer must be in the form the standard requires, covering the high current, switching and steep current impulse tests together with the long duration and operating duty tests. The document is applied across every voltage level from distribution to the highest transmission classes, and it is read together with the separate national standards for arresters in direct current and capacitor bank applications.