A transformation transforms elements of a source model to elements of a target model. Depending on the type of transformation, examples of source and target models include text files, code models, or UML models. When the source and target models are both UML models, the transformation typically converts the elements from one level of abstraction to another.
A transformation contains conversion rules, which convert one type of source element into one or more target elements. In addition to conversion rules, a transformation contains a mechanism that traverses the elements of the source model and that runs the appropriate rules based on the element type and rule-specific criteria. For example, a given rule might run only if the type of model element is a UML class with a specific stereotype. You might need to apply a particular UML profile to the source model before a transformation can successfully convert the source model elements into target elements.
A transformation configuration is an instance of a transformation that includes information that all transformations use, such as a unique name, the source, and the target of the transformation; it can also include properties that are specific to a given transformation. A transformation configuration has .tc as a file name extension. When you run a transformation, it uses the information that you provide in the transformation configuration.
Before you can run a transformation, you must create a transformation configuration. When you apply a transformation configuration, an instance of the transformation is created and runs with the properties that you define in that configuration, generating the output that you expect.
For more information about creating transformation configurations or running transformations, see the "Configuring transformations" or "Running transformations" topics for the transformation that you are using.