This International Standard provides fundamental terms and definitions in English and French applicable to cylindrical screw threads with profiles (in an axial plane) based on triangles. A list of Russian equivalent terms is given in annex A. NOTE - In addition to terms used in the three official ISO languages (English, French and Russian), this International Standard gives in annexes B and C, the equivalent terms in German and Italian; these have been included at the request of the technical committee ISO/TC 1, and are published under the responsibility of the member bodies for Germany, F.R. (DIN) and Italy (UNI). However, only the terms given in the official languages tan be considered as ISO terms.