The trace functionality is optional and must be turned on in the MOFScript preferences page. Here you also set the trace model generation directory and the block comment tag that will be used. The default tag is “//” which is applicable to e.g. java code generation.
The references to model elements are the basis of MOFScript traceability. All references to model elements that are used to generate a text file will be traced to the text file(s) they occur in. These traces are stored in the trace model and can be viewed e.g. in the Reflective Ecore model editor that comes with Eclipse.