[Bug 6452] New: scds extensibility

http://www.w3.org/Bugs/Public/show_bug.cgi?id=6452

           Summary: scds extensibility
           Product: XML Schema
           Version: 1.1 only
          Platform: PC
        OS/Version: Windows XP
            Status: NEW
          Severity: normal
          Priority: P2
         Component: SCDS: XML Schema Component Designators
        AssignedTo: holstege@mathling.com
        ReportedBy: johnarwe@us.ibm.com
         QAContact: www-xml-schema-comments@w3.org


My mental parser is having a hard time with how the extensibility of accessors
and axes is handled.

For example,
[19]    Axis       ::=           'schemaAttribute' '::' | 'schemaElement' '::'
| 
                             ...| ExtensionAxis
[23]    ExtensionAxis      ::=          QName '::'

When my code encounters the string "schemaElement::foo", how exactly does it
know whether to treat schemaElement as a QName and apply the current xmlns=
binding or to treat is as 'the special string' (which seems to be equivalent to
saying it is really a local name with an implicit namespace == XML Schema 1.1).
 The bifurcation of not using a QName for Schema-defined axes and then making
all extensions use QNames seems unnecessary (albeit, more compact in the normal
case perhaps).

I react pretty much the same way to accessors in general, and to the strings
returned by component-kind() (4.5.1 component-kind Accessor).  It seems like
they should all by QNames, with a Schema-defined namespace in the case of
entities defined by the Schema wg.

FWIW, this is not an academic issue at all.  Existing specs, e.g. SML, define
their own identity constraint schema components.  If it becomes necessary at
some point to reconcile them with SCDS, consumers would be getting back results
from component-kind(Identity‑Constraint Definition) of
"identity-constraint-definition" and (presumably)
component-kind(sml:Identity‑Constraint Definition) of
"sml:identity-constraint-definition" - which gets one back to the same
ambiguity I started with on how to distinguish what is, from the description I
see here, a string, from a QName that happens to lack an explicit ns prefix.


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Received on Monday, 19 January 2009 21:14:21 UTC