[tei-council] what is <classRef> supposed to do for attr classes?

I'm a bit confused by the use of PureODD's <classRef>. When the class being referred to is a model class, it would seem the intent is that it be used form within <content>, and the members of that model class can appear at this point in the content model. And, indeed, all 25 examples of <classRef key="model.*"> occur as descendants of <content>. When the class being referred to is an attribute class, it would seem the intent is that the attributes defined by the class are available to be used, as a group, by reference to the class name on classes/memeberOf/@key. And, indeed, all 3 examples of