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TAG ACTION-23: URIs for XML Schema datatypes

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Tue, 14 Feb 2012 13:04:28 +0000
To: www-xml-schema-comments@w3.org, www-tag@w3.org
Message-ID: <f5bvcn91s83.fsf@calexico.inf.ed.ac.uk>
This is a brief heads-up in anticipation of a longer exposition.

TAG ACTION-23 [1] tasks me with tracking the state of issue 1974 [2]
which I raised against the W3C XML Schema spec:

  We claim in Part 2 that e.g. http://www.w3.org/2001/XMLSchema#int is
  the name for the int type, but there is no anchor of that name in
  the namespace document for our namespace URI.

I subsequently proposed a resolution [3] to this issue which would
have placed anchors for all the XML Schema datatypes in the namespace
document retrievable from the XML Schema namespace URI, i.e.

  http://www.w3.org/2001/XMLSchema

As a result of recent TAG discussion [4], I now believe both my
formulation of the issue as quoted above, and my proposed resolution,
to be wrong.  My next message on this subject will go in to detail,
but the short version is simple. The relevant facts are these:

 1) There are not now, nor will there be when XML Schema 1.1 is
    approved, anchors for those names in the schema document for
    schema documents, which is retrievable from
    http://www.w3.org/2001/XMLSchema via content negotiation with
    Accept: application/xml

 2) Per the (X)HTML media types, the thing identified by URIs with
    fragment identifiers is an element in a document.

These facts mean that adding anchors to the namespace document as I
suggested and then proposed would be contrary both to an established
principle of web architecture and to simple semantic coherence:

 1) Because if we added such anchors they would be present in only one
    of two content-negotiable representations retrievable from the
    namespace URI, contra AWWW's statement that

  "representation providers must not use content negotiation to
   serve representation formats that have inconsistent fragment
   identifier semantics" [5]

 2) An element in a document (which is what e.g. the URI
    http://www.w3.org/2001/XMLSchema#int would identify in the
    namespace document under my proposal) is not a datatype, which is
    what the XML Schema spec. says it identifies.

So, I hereby withdraw the proposal in [3], and will amend my statement
of the issue [2] in Bugzilla forthwith.  A new proposal will follow in
due course.

ht

[1] http://www.w3.org/2001/tag/group/track/actions/23
[2] https://www.w3.org/Bugs/Public/show_bug.cgi?id=1974
[3] http://lists.w3.org/Archives/Public/www-tag/2007Sep/0058.html
[4] http://www.w3.org/2001/tag/2012/01/26-minutes.html#item02
    https://www.w3.org/2001/tag/2012/02/09-minutes.html#item05
[5] http://www.w3.org/TR/webarch/#frag-coneg
-- 
       Henry S. Thompson, School of Informatics, University of Edinburgh
      10 Crichton Street, Edinburgh EH8 9AB, SCOTLAND -- (44) 131 650-4440
                Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                       URL: http://www.ltg.ed.ac.uk/~ht/
 [mail from me _always_ has a .sig like this -- mail without it is forged spam]
Received on Tuesday, 14 February 2012 13:04:58 GMT

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