To examine the contents of the mapping project:
Mapping models, also called mapping files, are instances of Eclipse Modeling Framework (EMF) metamodels, also called Ecore models, that contain references to the metamodels that are being mapped. When you create a mapping project, the authoring tools create a mapping model in the project by using the input and output model or models that you specify. A mapping model has .mapping as a file name extension.
Mapping models are stored and serialized as XML files. The Problems view displays detailed error information about mapping models. In this view, double-click an item to open the mapping model in a text editor and view the line that contains the error. This method of troubleshooting is often easier than troubleshooting by viewing the mapping model in the editor area.