W3C home > Mailing lists > Public > w3c-sgml-wg@w3.org > June 1997

A possible fallback for namespaces

From: David G. Durand <dgd@cs.bu.edu>
Date: Fri, 13 Jun 1997 10:42:34 -0500
Message-Id: <v03007802afc7169eb58c@[205.181.197.93]>
To: w3c-sgml-wg@w3.org
When I started to write this I had the simple idea it would not be too
harmful (though I don't see the utility as large) to add colon to
namestart, for people to use today, and reserving double colon for future
expansion, once we figure out what namespaces are supposed to be.

But, after reading the very nice metadata proposal, I'm not convinced that
we really solve much that way.

The problem is that the same element and the same data in that element may
conform to _several_ namespaces. In fact, to the extent that my quick
reading of the proposal makes sense, it actually allows the creation of
semantic structures like that in its own context.

So attaching one identifier at the beginning doesn't solve the problem
without additional machinery.

The only problem that I can clearly understand from the namespace
discussion so far is one of attaching external meaning(s) to markup in
context. I still think that attributes already exist, and are the standard
way to do this. The problem is that there isn't a universal namespace for
attaching such attributes to elements.

Maybe we need a PI to attach an FPI or URI (whether of a human readable
spec, or a processor to be let vague in exactly the way that it is in
NOTATION) to an attribute name. Then that attribute name's presence on an
element means that the semantics associated with its value (as described in
or implemented by the FPI or URI) applies to that element.

In practice, we might be better served by just picking good attribute
names, and letting the marked sort out conflicts, but the PI would at least
serve a real need. Given that the URI identification would probably work
pretty much the way NOTATIONs do, there is some case for using a notation
declaration...


So my proposal would lead to declarations like:

<!NOTATION Netscape-wizardry PUBLIC "//NETSCAPE::Department of
Meta-Standards//NOTATION Meta Description of Meta Data Format//EN"
"http://defs.netscape.com/meta/meta/desciption/meta/DMS-MDMDF.class">

<?EXTERNAL-ARCH MDMDF Netscape-wizardry?>

These would allow applications that care about architectures (and know how
to deal with the MDMDF architecture, to interpret MDMDF attributes that
occur in the document instance.

I'm not sure that this is necessary -- we could just assign an attribute
name like com-netscape-MDMDF and be done -- but it seems to meet the
namespace requirements that I understand in a nicer way. Note that it also
uses the theory of URN/FPI and the practice of Architecture attributes, so
that we have _some tenuous_ theroretical/practical grip on it.

  -- David

_________________________________________
David Durand              dgd@cs.bu.edu  \  david@dynamicDiagrams.com
Boston University Computer Science        \  Sr. Analyst
http://www.cs.bu.edu/students/grads/dgd/   \  Dynamic Diagrams
--------------------------------------------\  http://dynamicDiagrams.com/
MAPA: mapping for the WWW                    \__________________________
Received on Friday, 13 June 1997 11:02:52 EDT

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