 SIZE (1..12), "/", INTEGER SIZE (1..31)} ::=134 Fig. 1.22 Refining an un-typed ASP specification to a typed one 1.6.5 Completeness The success of a modelling language depends on its completeness in the sense that all system properties concerning a particular task can be expressed in a single lan- guage. This is specifically SO for modelling languages that have a small semantic distance to design languages, since it is difficult to introduce a modelling language in addition to other design languages, if designers must use two languages instead of just one. The ideal situation is therefore that: The language is domain specific. There is only one modelling language to be used by each category of designers. The modelling language represents at least a company standard. Models can be fully automatically translated into models in another language on a lower semantic level. It is quite common in systems engineering that different languages are used for specifying different properties of a system. An example are the ITU-T languages MSC and ASN.1, used for describing interaction sequences and data types respec- tively. These languages satisfy the requirements for being standardized, but they deal only with partial aspects of systems modelling. Unless these languages are integrated in a common modelling language, mapping of fragments into program- ming languages and hardware description languages is an extra manual task that counteracts the purpose of modelling, both with respect to productivity and system quality. This is also recognized by modelling languages as e.g. SDL, which inte- grates MSC and ASN.1. 1.7 Summary AML is designed to fulfil most of these general requirements. It is definitely domain specific. It is complete enough to specify system components on a level of detail that matches software modelling languages. It is, however, not yet complete enough for simulation of telecom systems characteristics, in which case queue models and statistical data representation must be added to the language. Auto- matic tr