Sets out recommended uniform practices for the preparation of drawings and semiconductor devices, drawings which indicate the space which should be allowed for devices in equipment together with other dimensional characteristics required to ensure interchangeability. In addition to the rules for the preparation of drawings, the Standard includes appendices providing advice on definitions, reference letter symbols, examples of drawing, conversion of dimensions and selection of screw threads. The Standard is technically identical with and reproduced from IEC 191-1:1966.