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Bug 3714 - Over-general description of [element declaration] etc
Summary: Over-general description of [element declaration] etc
Status: CLOSED FIXED
Alias: None
Product: XML Schema
Classification: Unclassified
Component: Structures: XSD Part 1 (show other bugs)
Version: 1.1 only
Hardware: Macintosh All
: P2 normal
Target Milestone: ---
Assignee: C. M. Sperberg-McQueen
QA Contact: XML Schema comments list
URL:
Whiteboard: important, work
Keywords: resolved
Depends on:
Blocks:
 
Reported: 2006-09-13 01:58 UTC by C. M. Sperberg-McQueen
Modified: 2006-10-09 21:14 UTC (History)
0 users

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Description C. M. Sperberg-McQueen 2006-09-13 01:58:12 UTC
The [element declaration] and [type definition]
properties on elements are described as applying 
whenever an element is valid against an element
declaration / type definition.

On the face of it, the text implies that every
element must be validated against every element
declaration and type definition in the schema.

The text should say that the [element declation]
is present if the element is valid against its
context-determined declaration, and that the
value of the property is that context-determined declaration.
And so similarly for [type definition], with the 
added possibility of the value having been specified
in xsi:type.

The WG discussed this and agreed in principle to make 
such a change, at its meeting of 8 September 2006.
(Some WG members were, I think, inclined to believe that
the existing text is not really erroneous when read in
the proper light.  But they were unable to make others in
the WG see that proper light, and they were also willing
to countenance a change in wording, even if strictly, by
their lights, unnecessary.)

This bug report is for XML Schema 1.1.  The analogous
report for 1.0 is bug 3713.
Comment 1 C. M. Sperberg-McQueen 2006-10-06 00:13:25 UTC
A proposal to resolve this issue is at
http://www.w3.org/XML/Group/2004/06/xmlschema-1/structures.b3714.200609.html
(member-only link).

In essence, it (a) changes the prose that introduces properties
like [element declaration], replacing descriptions of the form

    If and only if an element information item is valid with
    respect to an element declaration as per Element Locally
    Valid (Element) (§3.3.4), then [the property is present]

with descriptions of the form

    If and only if an element information item is valid with
    respect to its governing element declaration as defined by
    Element Locally Valid (Element) (§3.3.4),

(b) makes clear that the [element declaration], [attribute
declaration], and/or [type definition] properties of elements and
attributes have the governing declaration and the governing type
definition as their value, if they have a value;

(c) introduces and defines the notion of an information item
being governed by a declaration and a type definition (this is
distinct from, although closely related, to the existing concepts
of context-determined declaration and Test(), but no effort is
made in the proposal to unsnarl the relations among all the
relevant terms; bug 3725 can be used to track that problem),

(d) replaces the terms 'local type definition' and 'actual type
definition' with 'instance-specified type definition' and
'governing type definition'

(e) specifies how the governing declaration and the governing
type definition are found for elements and attributes;

(f) moves the definition of 'context-determined declaration' out
of the Validation Rule: Schema-Validity Assessment (Attribute),
since the definition is used outside that validation rule;

(g) removes the clauses which suggest that an element cannot be
valid against any element declarations except its
context-determined declaration or a stipulated declaration;
replace them with a reference to the element's governing
declaration;

(h) introduces the term 'validly substitutable' to describe
the relation between types which must hold when an xsi:type
attribute is used;

(i) makes some minor editorial changes in passing.
Comment 2 C. M. Sperberg-McQueen 2006-10-09 21:11:46 UTC
The proposal described in comment #1 was accepted by the WG on
6 October 2006; the appproved wording is in the status quo version
of the spec and will be included in the next public release of the
document.