. In engineering telecom systems, sysnet models must be separated into two classes, standardized system models and applied systems models. In this engineer- ing discipline more than in others, a large and important part of the early develop- ment is not done in development projects, but through standardization work, the result of which becomes documented in standardized system models. Standardized system models are sysnet models that are defined by international standardization bodies, such as the ITU-T, the European Telecommunications Standards Institute (ETSI) and the Object Management Group (OMG). Standardized system models act as the main requirements on manufacturers solutions, which are described as applied system models. Applied system models have a refinement relation to standardized system mod- els. Such a relation describes all kinds of modifications, and selection amongst the manufacturer's options and added functions that are needed to completely define a system solution. Characteristic differences between standardized and applied sys- tem models are: Standardized system models normally do not deal with physical or spatial prop- erties of systems. Standardized system models (deliberately) never deal with execution functions, e.g. which processors and platforms must be used to support and execute the functions defined by the standard. We say that standardized system models do not describe the processing dimension of a system. In the applied system model, the processing dimension is, of course, an important aspect of the model. Standardized system models usually define only a small part of all functions that will be included in an applied system model. An applied system model might not include everything that is defined by the standardized system model. An applied system model often has a deeper structure than what is defined by the corresponding standardized system model (depending on the decision of the modeller). The primary reason is that the introduction of a processing dimension normally also intr