Of course, transformation definitions need to be written in a well-defined language to allow transformation tools to read and execute the transformations. A language in which these definitions are written is called a transformation definition language . In such a language you can define transformations based on the metamodels of the languages. Because it works on the metalevel, a transformation definition language is a metalanguage .
The MDA framework is obviously not complete without a transformation definition language. In Figure 9-5 the complete MDA framework is shown. This is identical to the extended MDA framework introduced in section 8.3.1, with the addition of the transformation definition language.
Figure 9-5. The complete MDA framework