An OPC UA application shall implement all mandatory ConformanceUnits in a Profile in order to be compliant with the Profile. Some Profiles contain optional ConformanceUnits. Optional means that an application has the option to not support the ConformanceUnit. However, if supported, the application shall pass all tests associated with the ConformanceUnit. If an OPC UA application desires to be listed as supporting the optional ConformanceUnit then it shall include any required information model items in the configuration provided for certification testing. The test result that is generated by the certification testing lists all optional ConformanceUnits and whether they are supported or not by the tested OPC UA application.