Applies to the terminal markings for the main circuits of valve device stacks and assemblies and of factory assembled integrated convertor equipment. The terminal markings refer to stacks, assemblies and equipment comprising semiconductor valve devices. Specifies a logical alphanumeric marking system for the identification of the external terminals of the main power circuits in a stack, valve element assembly of integrated convertor equipment, which is applicable for the purpose of reference in circuit diagrams, catalogues, descriptions and information exchange and storage. The contents of the corrigendum of December 1995 have been included in this copy.