This document provides methods for the gauging of ISO UNJ threads complying with ISO 3161. Other methods of ensuring that the product is within the specified limits can be used, provided that correlation with the specified gauges is established.nd edition 2017-03 Aerospace — UNJ threads — Gauging Aéronautique et espace — Filetage UNJ — Vérification par calibres Reference number ISO 15872:2017(E) ？ ISO 2017 ISO 15872:2017(E) COPYRIGHT PROTECTED DOCUMENT ？ ISO 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized