W3C home > Mailing lists > Public > www-tag@w3.org > February 2002

XML-SW, a thought experiment

From: Tim Bray <tbray@textuality.com>
Date: Wed, 06 Feb 2002 20:43:10 -0800
Message-ID: <3C6205DE.2000901@textuality.com>
To: www-tag <www-tag@w3.org>
A discussion on www-tag starting at


developed into some interesting discourse on what a next rev of XML
might look like.  Following on this, a thought experiment
named XML-SW appears at


  XML-SW =  XML 1.0 2nd ed.
          - DTDs (and therefore entities)
          + namespaces
          + xml:base
          + the infoset.

Pulling it together took maybe a day all told, mostly sitting
in airplanes.  It was immensely enjoyable, and from a purely
rhetorical/tutorial/stylistic point of view, I think XML-SW
works better than most of its component parts (with the possible
exception of xml:base, a remarkably graceful piece of work).
Among other things:

All the endless circumlocutions around parameter entities: gone.
"For interoperability": gone.  The attribute value normalization
and line-end handling migrate into the infoset, where they belong.
xml:base goes with xml:lang and xml:space into a section about
reserved attributes.  Namespaces go into the discussion of
elements and attributes, where they belong.  "standalone=": gone.
There's a nice "other markup" section for comments, PIs, and
a vestigial doctype declaration.  The vestigial doctype is defined
purely syntactically and has no internal subset - a low-cost way to let
people do DTD validation with XML 1.0 processors.  The conformance
section has real content, including the error-handling, which has
migrated out of its awkward home in the definitions list.  All the
links out of infoset and namespaces are internal.

There are a million stylistic cleanups, ranging from bookkeeping -
all example URIs are from example.com - to the excision of rhetorical
tumors - there is no discussion of the relationship of namespaces
to sets.

Aside from the massive change in losing DTDs & entities, I hope
there are no other normative or semantic changes between XML-SW
and the specs that went into it.  If there are, that's a bug.
The temptation to introduce JUST A FEW little obvious improvements
that nobody could possibly disagree with is overwhelming,
but that is a slippery slope leading into the most noisome of
ratholes.  Put another way, data and software that conform
to XML-SW, aside from the difficult question of what goes in
<?xml version="?", should in all respects conform to all the W3C
recommendations that went into it.

One or two people have favored me with feedback and suggestions;
they have my thanks but I won't mention their names here, as nobody so
far - not even me - has taken the stand that this is a good idea.

Unfinished work:
- roll in the improved character and name definitions from Blueberry.
- link-check; there are almost certainly a few broken links
- Turn XML-SW into an XML-SW document; currently it has an internal
   subset and the XSLT formatter relies on ID attributes. Then again, the
   first few drafts of the XML spec were actually SGML.

Received on Wednesday, 6 February 2002 23:42:13 GMT

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