The International Vocabulary for Metrology (VIM) [JCGM 200] defines the general concepts and the associated terms for metrology. Chapter 3 of VIM describes devices for measurement. A measuring instrument is thus a device used for making measurements, alone or with one or more supplementary devices. A measuring system consists of a set of one or more measuring instruments and often other devices, including any reagent and supply, assembled and adapted to give information used to generate measured quantity values within specified intervals for quantities of specified kinds. A measuring system may even consist of one single measuring instrument only.

The standards of Geometrical Product Specification (ISO GPS) are used to define the geometric requirements for workpieces in technical specifications and the requirements for their verification [ISO 14638]. The verification is mainly done by measurements. General concepts and requirements for the used measuring equipment define ISO 14978. The described measuring equipment is also called a measuring system. This leads to the term Geometric Measurement System (GMS). A GMS is a measuring system according to [JCGM 200] performing geometrical measuring tasks. The measurement in production is often automated.

OPC UA offers the opportunity to integrate GMS into production according to the described path in Figure 1.