TS EN ISO 2692

TS EN ISO 2692 defines the maximum material requirement (MMR), the least material requirement (LMR) and the reciprocity requirement (RPR) within geometrical product specifications (GPS) and geometrical tolerancing. It is a key reference for understanding how size and geometry are linked when a feature must satisfy a functional design intent.

What these requirements mean in practice

In general technical terms, MMR is associated with the condition in which a feature contains the most material, while LMR refers to the condition with the least material. RPR addresses the reciprocal relationship between these conditions. These concepts are used for linear features of size, especially cylindrical features and features formed by two parallel opposite planes, where dimensional limits and geometrical deviation must be considered together.

The standard states that these requirements can only be applied to linear features of size of cylindrical type or two parallel opposite planes type. That boundary matters because MMR and LMR are not just size concepts: they are used to connect allowable geometric variation with the intended function of a part, such as assembly or minimum wall thickness.

Functional use in design and verification

From a general engineering perspective, these requirements are valuable wherever interchangeability, fit and structural integrity depend on the interaction between size and form. MMR is often used to support assembly-related design intent, while LMR is useful where a minimum remaining material condition must be preserved. RPR provides the reciprocal framework that helps express these relationships consistently in the GPS language.

This document is primarily a definitional and conceptual standard rather than a manufacturing instruction. It clarifies how the three requirements are understood and where they may be applied, helping drawings, specifications and inspection-related communication remain technically consistent.