ISO 25378 defines general terms for geometrical specifications, characteristics and conditions. These definitions are based on concepts developed in ISO 17450-1 and ISO 22432 and they are given by using a mathematical description based on Annex B of ISO 17450-1:2011.
This International Standard is not intended for industrial use as such among designers, but is aimed to serve as the “road map” mapping out the requirements based on geometrical features, thus enabling future standardization for industry and software makers in a consistent manner.
This International Standard defines general types of geometrical characteristics and conditions which can be used in GPS. These descriptions are applicable to
— a workpiece.
an assembly,
a population of workpieces, and
– a population of assemblies,
These definitions are based on concepts of operators and the duality principle contained In ISO 17450-1 and ISOITS 17450-2 and on the description of types of geometrical features defined in ISO 22432.
Conceptually, these specification operators can be used as specification operators or as verification operators (duality principle).
This International Standard is not intended to define GPS specifications, symbology or other types of expression.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3534-1:2006, Statistics — Vocabulaiy and symbols — Part 1: General statistical terms arid terms used in probability
ISO 3534-2, Statistics — Vocabulary and symbols — Part 2: Applied statistics
ISO 17450-1:2011, Geometrical product specifications (GPS) — General concepts — Part 1: Model for geometrical specification and verification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3534-1, ISO 3534-2 and ISO 17450-1 and the following apply.
3.1 geometrical specification
expression of a set of one or more conditions on one or more geometrical characteristics
NOTE1 A specification can express a combination of individual conditions on an individual characteristic or a population condition on a population characteristic.
NOTE 2 A specification consists of one or more single specifications. These single specifications can be individual specifications, population specifications or any combination.
3.2 condition
combination of a limit value and a binary relational mathematical operator.ISO 25378 pdf download.