And in this case we can make a permanent variation. This looks good since we want to integrate with Batory's techniques anyway and this example shows how we can express his layered systems in our model.
Inheritance does single class variation permanently.
Batory does multiple class variation at permanently. Inheritance and Batory express variation by adding and overriding methods and we, in addition, express variation by executing additional code during a traversal at run-time. Karl From Implementing Layered Designs with Mixin Layers by Batory et al. From Container to Node.