Re: [xml-dev] Re: ID/IDREF makes XML generation NP-hard

> Thus it seems that they share the same proviso as with Henry's analysis: 
> Henry's analysis seems to apply to DTDs with fixed IDs or fixed IDREFs, 
> and this paper applies to where there is an outside fixed set of constraints 
> such as keys and foreign keys.  

Not sure I see the distinction between keys and ID and foreign keys and
IDREF...

The paper does talk about constraints on the contents of a single XML
file if I remember correctly.

Christian