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[Fwd: simple barenames for schema component designators] last call: "XML Schema: Component Designators" [abstractComponentRefs-37]

From: Dan Connolly <connolly@w3.org>
Date: Thu, 31 Mar 2005 13:41:43 -0600
To: www-tag@w3.org
Message-Id: <1112298103.15073.2.camel@localhost>
In the TAG/Schema discussion of abstractComponentRefs-37 and
XML Schema component designators in March 2004...
... I gave a use case, referring to user-defined datatypes from OWL
ontologies, and proposed requiring support of barenames (e.g. #sku). 

XML Schema component designators recently went to last call.

The last call design doesn't meet the barename requirement, so I
sent the attached comment.

The usecase can perhaps be accommodated without the requirement.

I don't know if there's any Web Architecture principle related to
my requirement, but I think the general principle of "keep
the simple things simple" applies.

I don't know if my comment is one that the TAG should take a position
on, but I encourage other TAG members and www-tag participants
to review the schema component designators spec and send comments.

Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E

attached mail follows:

Please allow barename fragments to be used as schema component designator
right hand sides. For example #over17 in


If they're already allowed, please make it more clear that they
are; my reading of

  3.1 Schema Component Designator Syntax

is that they're not.

We discussed this in March 2004...

DC: Most pressing use case is pointing at user-defined datatypes. First
design that occurs to me is #sku. Why not?

MSM: Multiple top-level symbol spaces. #sku could be type, element,
attribute, notation, attribute groups, named model groups...

DC: OK, so don't do #sku to do that. Advise users to not have two
top-level things named the same.



There seems to be little or no acknowledgement of the case
case of user-defined datatypes in OWL. The only thing I see is:

  "RDF assertions about types, etc".

Please cite this section of the OWL recommendation among your

"Because there is no standard way to go from a URI reference to an XML
Schema datatype in an XML Schema, there is no standard way to use
user-defined XML Schema datatypes in OWL."
  -- http://www.w3.org/TR/2004/REC-owl-semantics-20040210/syntax.html#2.1

And acknowledge this example from the DAML+OIL submission among
your use cases:

<xsd:simpleType name="over17">
  <!-- over17 is an XMLS datatype based on positiveIntege -->
  <!-- with the added restriction that values must be >= 18 -->
  <xsd:restriction base="xsd:positiveInteger">
  <xsd:minInclusive value="18"/>

<daml:Class rdf:ID="Adult">
  <daml:intersectionOf rdf:parseType="daml:collection">
    <daml:Class rdf:about="#Person"/>
      <daml:onProperty rdf:resource="#age"/>
      <daml:hasClass rdf:resource="http://www.w3.org/TR/2001/NOTE-daml+oil-walkthru-20011218/daml+oil-ex-dt#over17"/>

 -- http://www.w3.org/TR/2001/NOTE-daml+oil-walkthru-20011218/#9

I still can't see why the design chosen in DAML+OIL shouldn't be
standardized in the XML Schema Component designators spec, so as
I say, please change the design too.

Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Thursday, 31 March 2005 19:41:45 UTC

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