i run in this inconsistency when I was plying with permisions

I have one category with some terms assigned to content type foobar. Each role can use exact one term. So it is not possible for s.o. who only can use term 'bar' to edit the nodes of another group with the term 'foo'. This works fine.

But: If there comes someone with the permision "edit foobar content" and wants to edit the node with term ID foo assigned but don't have permission to set 'foo', he can and have to set another value. If he is dooing so wee will now have two termids assigned to this node. But this we dont want. Because we have now an inconsistence.

(this happened to me there: The situation like I described in http://drupal.org/node/207439)

This should be resolved in the drupal way with the filters. If you don't have permission to set the php filter but you want to edit a node where the filter is set you cant.