This section introduces the "OPC UA Information Model for Geometric Measurement Systems". This Information Model provides the necessary ObjectTypes to model the interface of a Geometric Measurement System with the hierarchy as illustrated in Figure 16 (nodes of GMS marked in yellow, whereas nodes of the OPC UA Information model of machine tools are marked in blue/grey). The model is based on the OPC UA model of machine tools, so the most important types are (subtype of) types of the machine tool model.

There are ObjectTypes that are used to identify the GMS (GMSIdentificationType), to monitor the GMS (GMSMonitoringType), to manage the production (ProductionType) of the GMS, to handle the Equipment of the GMS (GMSEquipmentType) and to give notification on the status of the GMS (NotificationType).

Additional to the types adopted from the machine tool information model, there are types for the Result Management (GMSResultManagementType) which is based on the result transfer model of OPC UA for Machinery.

**Figure ****16** **– Overview of the Information model of a Geometric Measurement System**

The ObjectType hierarchy and the important children of an ObjectType of this Companion Specification are shown in Figure 17 - Figure 22. Objects from external specifications are positioned within greyish-blue boxes.

**Figure ****17** **– Node structure of the Identification in the Geometric Measurement System interface**

**Figure ****18** **– Node structure of the GMSMonitoringType**

**Figure ****19** **– Node structure of the Production in the Geometric Measurement System Interface**

**Figure ****20** **– Node structure of the Equipment in the Geometric Measurement System Interface**

**Figure ****21** **– Node structure of the Notification in the Geometric Measurement System interface**

**Figure ****22** **– Structure of the Result Management in the Geometric Measurement System interface**