A simple transformation is the update of an old callchain file.
You can start by selecting you old callchain file and select New -> other
select the target container and the input model. If your project isn't
an ATL project you can add the ATL nature to the project.
After finishing the wizard the nessesary files are created and you can open up the callchain_diagram file.
you can start the transformation via context menu on the call element
The old model (IN) conforming to the old meta model will be transformed by the ATL_FLOW2ATL_FLOW to a new model (OUT) conforming to the new meta model.