[Termtools] ceta(2) - selective context closure?

Dear all, can I express in CPF (for Ceta-2) that I want to apply "flat context closure" to a subset of rules only? specifically, I want this for rules with empty lhs or rhs, as it seems to increase the power of matrix interpretations. (as shown by Aprove in TC 23). I am looking at http://cl2-informatik.uibk.ac.at/rewriting/mercurial.cgi/IsaFoR/file/8250228... but the example seems to close all rules. I guess I can indeed context-close all rules uniformly, and use the same interpretation, to remove the same rules. But perhaps I want other methods that refer to the original rules. Well it's a bit late anyway. - J.