[tei-council] Further purification

[Syd Bauman]

I like (a) and (b) a lot. I think I like (c), too, but less sure, for
two reasons:

1. worried it can result in confusion

2. I don't see off top of my head how it would be implemented.

But if it is implementable and well documented, I am inclined to say
we should go for it.

> Thinking about pure ODD, it occurs to me that it would be very useful
> if one could treat <classRef>s in the same way as <moduleRef>s --
> i.e. by adding the attributes @include and @exclude to <classRef> it
> would be possible inside an elementSpec to do things like
> 
> (a) <classRef key="att.global" except="att.linking"/>
> 
> as a short way of suppressing a bunch of attributes
> 
> or
> 
> (b) <classRef key="att.linking" include="next prev corresp"/>
> 
> as a neat way of saying which attributes I do want.
> 
> Similarly, for model classes, it would be really nice to be able to
> say inside a content model something like
> 
> (c)  <classRef key="model.choiceLike" except="seg"/>
> 
> which would not interfere with seg appearing elsewhere in a content 
> model, but would suppress it from inside <choice> in a tidy way.
> 
> Anyone object to my adding these two attributes as part of the pure
> ODD work?