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Bug 2861 - RQ-38 Add co-constraints (coconstraints)
Summary: RQ-38 Add co-constraints (coconstraints)
Status: RESOLVED FIXED
Alias: None
Product: XML Schema
Classification: Unclassified
Component: Structures: XSD Part 1 (show other bugs)
Version: 1.1 only
Hardware: Other All
: P2 normal
Target Milestone: ---
Assignee: C. M. Sperberg-McQueen
QA Contact: XML Schema comments list
URL:
Whiteboard: important, hard
Keywords: resolved
Depends on:
Blocks:
 
Reported: 2006-02-11 01:58 UTC by C. M. Sperberg-McQueen
Modified: 2007-08-03 18:50 UTC (History)
0 users

See Also:


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Description C. M. Sperberg-McQueen 2006-02-11 01:58:20 UTC
Add the ability to define and enforce co-constraints on attribute
values, or on attribute values and sub-elements. For example, if
attribute a has value foo, the attribute b must have one of the values
fuzz, duz, or buzz; but if attribute a has value bar, the attribute b
must have one of the values car, far, or tar. Or: if attribute href
occurs, the element must be empty; if it does not occur, then it must
have type phrase-level-content.

See
http://lists.w3.org/Archives/Public/www-xml-schema-comments/2000OctDec/0040.html:
LC-193 Response.

See
http://lists.w3.org/Archives/Public/www-xml-schema-comments/2001AprJun/0175.html:
R-7 in Errata List.

This issue was also formerly known as co-occurrence (RQ-27; removed)

Input from Straw Poll O-13

Opportunistic desideratum for 1.1: At our meeting in August 2002, some
members of the WG felt that co-constraints needed to be a requirement
for 1.1, others that the feature is too complex to design in the time
available and with the compatibility constraints agreed for 1.1.  Some
WG members thought an 80/20 solution would be easy to specify, and
undertook to demonstrate this by doing so.

This item was abandoned in the meeting of 2004-03-25
(http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2004Mar/0133.html).

A request to reopen it was was received on 25 May from Fabio Vitali
(http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2004May/0066.html)
(member-only link), and the WG has informally agreed to do so.  A
proposal from Paul Biron was received at the end of January 2006
(http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2006Jan/0137.html)
[member-only link]; there is also the work done by Fabio Vitale and
others (http://tesi.fabio.web.cs.unibo.it/schemapath).
Comment 1 C. M. Sperberg-McQueen 2006-06-26 12:14:03 UTC
The Working Group agreed to add support for simple Schematron-style
check clauses, at the face to face meeting in Redwood Shores, April
2006.

Accordingly I'm changing this from needsAgreement to needsDrafting.
Comment 2 C. M. Sperberg-McQueen 2007-07-25 03:04:36 UTC
The Schematron-style assertions mentioned in comment #1 were
added to the spec in late summer 2006, and are reflected in the
public working draft of August 2006.  This entry should have been
updated then.

The Working Group has also agreed in principle to add conditional
type assignment as a second class of co-constraint; we reached
consensus on the technical content of the mechanism at the 
face to face meeting in Pisa in June 2007.

A wording proposal for conditional type assignment has now been drafted and
is at http://www.w3.org/XML/Group/2004/06/xmlschema-1/structures.cta.rt.200707.html (member-only link).  Accordingly, I'm changing the keyword on this entry
from needsDrafting to needsReview.
Comment 3 C. M. Sperberg-McQueen 2007-08-03 18:50:59 UTC
The wording proposal for conditional type assignment mentioned in comment
#2 was accepted by the Working Group at its call of 27 July 2007,
with amendments.  The largest of these amendments was that Type
Alternatives should be components, not property records, and that
they should carry their own annotations. 

So I'm marking this issue as RESOLVED / FIXED.