That use(s) needs to be spelled out better.  I repeat:  the problem 
with XML development is still the lack of requirements.  If that 
has to be expressed in terms of "What SGML DTDs Don't Do and 
We Need", so much the better.  Requirements give more people time 
to plan designs and submit proposals. 
> In the area of document grammar specification, XML-Data offers
> no functionality which cannot be duplicated by extensive use of
> parameter entities.  But it provides that functionality in a
> transparent (in some cases MUCH more transparent) way, and in my view
> that makes it worth bothering.
Then SGML/XML can do it.  I'm not sure transparency isn't 
an eye of the beholder idea like complexity.  Tim notes a 
big shift in audience SGML literacy.  I'm not sure what to 
make of that remark, but if we are teaching two ways to 
do the same thing before the first XML spec is even 
published with regards to schemas, we're screwing up in a 
big way.
I need a better definition of "transparency".  That 
is qualitative, it seems, and all qualitative requirements 
have to be sold by compelling example because that is 
often chosen on taste.
  
> Yes, but what about the Trans-Bulgarian Women's Quiltmakers' Club? :-)
Hey, my grandmother was a quilter!
len