中文摘要：

描述了几何要素的本征方向和本征自由度概念、几何要素自由度的表示方法和约束自由度的计算规则。根据基本几何元素的几何特征以及与基准要素的位置关系确定了几何要素的本征方向，根据几何量测量原理，提出了基准要素约束自由度的计算方法，建立了基准体系约束自由度的计算规则。根据公差类型与基准要素和目标要素的关系，建立了公差设计正确性、完整性验证的具体规则，提出了基于自由度分析的公差标注正确性验证方法。

英文摘要：

The intrinsic direction of geometric feature,the representation method and calculation rules of DOF of geometric feature were proposed.The intrinsic direction of geometric feature was de-termined based on the geometric characteristics and position relations among toleranced geometry fea-ture and datum geometry feature.According to the geometric measurement principles,the computa-tion method of constraint capability of datum feature to the DOF of target feature was proposed,and the calculation rules of constrained DOF of toleranced features were proposed by datum reference frames.The tolerance specification validation method were proposed according to the relationship a-mong tolerance type and geometry of the datum and target entity ,and the correctness and complete-ness validation rules were discussed against the dimensioning and tolerancing standards and against good practice rules in industries.