TS EN ISO 5459

TS EN ISO 5459 is the standard for datums and datum systems within geometrical product specifications (GPS), defining how these reference elements are designated and understood in technical product documentation. In practice, datums provide the geometric framework used to control a part’s orientation, location, and functional relationship to other features.

How datums and datum systems work in GPS

In general technical terms, a datum is a theoretically exact or derived geometric element—such as a plane, axis, or point—that serves as a reference for measurement and verification. A datum system combines multiple datums to create a more complete frame of reference, especially for parts that must be located or assembled with a specific functional orientation. This distinction matters because a single datum rarely defines enough information for a complex component.

According to the scope of ISO 5459:2011, the standard specifies the terminology, rules, and methodology for indicating and understanding datums and datum systems in technical product documentation, and it includes explanations to support user understanding of the concepts involved. It also defines the specification operator used to establish a datum or datum system. The verification operator may take physical or mathematical forms, but it is not the subject of ISO 5459:2011. Detailed rules for maximum material requirement and least material requirement for datums are given in ISO 2692.

• Designation and interpretation of datums in technical documentation
• Rules and terminology for datum systems in GPS
• Conceptual separation between specification and verification
• Functional reference frameworks for geometry control
• Related requirements for maximum and least material conditions addressed in ISO 2692