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   Re: [xml-dev] Re: AF and namespaces, once again (was Re: [xml-dev] There

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Steven R. Newcomb scripsit:

> Exactly what I'm wondering, Len.  I think so, but I'm
> not comfortable enough with RNG yet to commit myself
> on this question.

I am doing a bit of thinking about what AFNG (to go
with RNG) might look like.  Preliminary sketch soon.

> (And when someone does
> this, typically someone else says, "You mean CONCUR?",
> whereupon everyone present makes a rude noise.  The
> CONCUR feature of SGML was an earlier attempt to
> address some of the same requirements.)

If I understand this, I actually reinvented CONCUR a couple
of years ago, when I was first thinking about possible ways
of representing non-hierarchical structures.  The trick
was to choose a Thoroughly Useless Name Char (I forget
what I picked originally, but U+06DD ARABIC END OF AYAH
will do nicely), and then represent multiple hierarchies
as follows:

1) Every distinct hierarchy gets a distinct name, for use
in making it real later.

2) Every start-tag is represented as an empty-tag with
an element type of HierarchyName+Useless+RealName.

3) Every end-tag is represented as an empty-tag with
an element type of HierarchyName+Useless+RealName+Useless.

4) Every empty-tag is represented by a start-tag followed
by an end-tag.

5) The whole document is wrapped in a new root element which
marks it as being multiple-hierarchy.

Then it is easy to pull out a specific hierarchy, by ignoring
tags with the wrong hierarchy name and converting the good
ones to proper start-tags and end-tags.

Likewise it is easy to "bias" toward a particular hierarchy,
by converting the tags of the specified hierarchy as above,
but leaving the other tags alone.

This scheme predates namespaces.

John Cowan           http://www.ccil.org/~cowan              cowan@ccil.org
Please leave your values        |       Check your assumptions.  In fact,
   at the front desk.           |          check your assumptions at the door.
     --sign in Paris hotel      |            --Miles Vorkosigan


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