几何产品规格（GPS）——几何公差——基准和基准体系

[中文适用范围]： 本文件规定了技术产品文档中基准和基准体系表示和理解的术语、规则和方法。该文件还提供解释，帮助用户了解涉及的概念。 [外文原描述]： This document specifies terminology, rules and methodology for the indication and understanding of datums and datum systems in technical product documentation. This document also provides explanations to assist the user in understanding the concepts involved. This document defines the specification operator (see ISO 17450-2) used to establish a datum or datum system. The verification operator (see ISO 17450-2) can take different forms (physically or mathematically) and is not the subject of this document. NOTE The detailed rules for maximum and least material requirements for datums are given in ISO 2692.