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Re:Can we be more concrete...



[David Durand]
>No, but we can make reasonable assumptions about what certain implementors
>are likely to do... If Netscape were to immediately see the value of
>rigorous DTDs I would fall down dead from shock. Separate stylesheets =>
>two HTTP hits already. This will be a tough sell... The chance people would
>accept 3 hits per document seems very low to me.

>We may yet have to bite the bullet and allow stylesheets within
>documents: which is a very bad idea, I think.

Can you explain why David?

>But I don't see how we can
>require DTDs for linking, and claim to have eliminated them from XML -- at
>least in the web context, linking is a hard requirement.

(Trying to anticipate the though processes of non-SGML savvy developers:-)

XML describes a tree structure.
A sub-tree, when considered a root is a perfectly valid tree.

Simple to understand stuff. "Technology FOO used to describe Technology FOO".
Most developers grin when they read things like that. It occurs all over
the place in software they use on a daily basis.

Going further:-

.  A single XML tree can cleanly contain multiple trees. One for
  "real" data. Others for data about data. Bits about bits (in Negroponte-speak)

.  Hypertext info. (i.e. AF stuff) can be encoded in XML and housed in
   a sub-tree. This sub-tree serves to express how the body sub tree is 
   decorated with attributes for Hypertext semantics.

.  Rendering Style info can be encoded in a sub-tree.

.  Hitherto-unthought-of-killer-application semantics can be 
   encoded in a sub-tree.

For *valid* as distinct from well-formed XML I have the option of achieving
this via fixed attributes in the DTD as per HyTime approach.

Pros:-
        Single HTTP hit.
        Developer friendly (IMO)
        No need for the DTD at Browser end in order to do Hypertext or any
        other document architecture.

Cons:-
        Duplication of hypertext info in every instance of a given AF set.
        How is the hypertext sub-tree recognised. Reserved GI names?
        How do browsers distinguish between data and meta-data for rendering
        purposes?

From a document management perspective, could meta-data XML docs be stored
as separate entities on the server side and merged with the main doc for
HTTP "on-demand". (I remember Eliot talking on CTS about using SPAM to do
this with HTML).

Given that displaying a document with hypertext links is a "rendering" do
we have to consider how Hypertext functionality will impact on rendering
functionality? An XML savvy browser will receive its Hypertext meta-data
somehow. It needs to know that it should not be rendered.

Finally, now that I am loosing the run of myself completely, why not allow
an XML encoding of the DTD to be an optional way of creating valid XML???


Happy new year to all,
Sean Mc Grath
digitome@iol.ie
Sean Mc Grath
digitome@iol.ie
Digitome Electronic Publishing
Developers of IDM - Next Generation SGML Transformation Technology
http://www.screen.ie/digitome