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Bug 4348 - Remove single-ID-attribute rule
Summary: Remove single-ID-attribute rule
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:
Keywords: resolved
Depends on:
Blocks:
 
Reported: 2007-02-23 19:08 UTC by C. M. Sperberg-McQueen
Modified: 2007-05-02 01:06 UTC (History)
0 users

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Description C. M. Sperberg-McQueen 2007-02-23 19:08:46 UTC
Like XML Schema 1.0, and like XML DTDs and SGML DTDs before it, XML Schema 1.1
forbids schema authors to declare more than one attribute of an element as
having type ID.

This restriction never made much sense, and it's currently getting in the way
of users as various as the HTML Working Group and the Web Services Policy
Working Group, as well as anyone else with an existing XML vocabulary with
defined ID attributes who would like to make it possible for authors to use
xml:id in addition to, or instead of, their existing ID attributes.

As we have done in other cases where we have decided not to enforce restrictions
imposed by our predecessor languages, we should add a note mentioning that
declarations with multiple ID attributes can't be translated into DTD
notation without loss.  

But we should then drop the current restriction and allow multiple
ID attributes on a given element.
Comment 1 Felix Sasaki 2007-03-05 04:10:55 UTC
From my experience in the WS Policy WG I can agree with Michael that having no "single-ID-attribute" rule would be very useful. See http://www.w3.org/2007/02/ws-policy.xsd for an example of the need for this functionality: The <Policy> element contains an attribute extension point <xs:anyAttribute namespace="##any" processContents="lax"/>, since the specifications needs to allow for Policy identification ( http://www.w3.org/TR/ws-policy/#Policy_Identification ) with xml:id or the wsu:Id attribute. It would be good to get rid of this extension point and just have two attribute declarations.
Comment 2 Sandy Gao 2007-04-13 16:56:49 UTC
During the 2007-03 F2F meeting, the working group resolved this issue by approving a proposal that removed the "single-id-attribute" rule. Marking this issue as "fixed" accordingly.
Comment 3 C. M. Sperberg-McQueen 2007-05-02 01:06:14 UTC
As the originator of this comment, I confirm that I am content
with the resolution adopted by the Working Group.