AccessControl

Turns out (long discussion with Norm) that AccessControl is implimented using both classifiers and descriptors. Owner is a classifier. Defining user groups is handled by classifiers. Identifying the accessible commands is done in the descriptor.

So it looks like I can still use a Topic as a DescriptorUnit. I just need to define more classifiers. (Classifiers seem to pop up everywhere. This is because a classifier is specific to a type of relationship.)

See http://www.compstrm.org/wiki/uuid/ms6ad8Pnf+n3R4-u0X58ut+q for details.