Re: Attribute Default Value

Hi Henry,

     Thanks for your response on this - sorry for the long delay in my 
reply.

     I think it's interesting to note that Appendix D of "XML Schema: 
Structures" [4] requires, as a precondition for assessment, Attribute 
Information Items with [local name], [namespace name] and [normalized 
value] properties.  However, the Infoset that results from schema 
assessment may contain Attribute Information Items that do not have a 
[normalized value] property.  In other words, the Infoset that results 
from schema assessment cannot generally be the subject of schema 
assessment itself.

Thanks,

Henry
[4] http://www.w3.org/TR/xmlschema-1/#infoset
------------------------------------------------------------------
Henry Zongaro      XML Parsers development
IBM SWS Toronto Lab   Tie Line 969-6044;  Phone (905) 413-6044
mailto:zongaro@ca.ibm.com


To: zongaro@ca.ibm.com
Cc: www-xml-schema-comments@w3.org
From: ht@cogsci.ed.ac.uk (Henry S. Thompson)
Date: 22 Nov 2001 13:21:32 +0000
Message-ID: <f5b1yirym8z.fsf@cogsci.ed.ac.uk>
Subject: Re: Attribute Default Value

zongaro@ca.ibm.com writes:

> Hello,
> 
>      According to 3.4.5 "Complex Type Definition Information Set 
> Contributions" of "XML Schema:  Structures" [1]
> 
> For each attribute use in the {attribute uses} whose {required} is false 
and whose {value constraint} is not ·absent· but whose {attribute 
declaration} does not match one of the attribute information items in the 
element 
> information item's [attributes] as per clause 3.1 of Element Locally 
Valid (Complex Type) (§3.4.4) above, the post-schema-validation infoset 
has an attribute information 
> item whose properties are as below added to the [attributes] of the 
element information item. 
> 
> 
> The section goes on to list the properties for such an attribute 
> information item as [local name], [namespace name], [schema normalized 
> value], [schema default], [validation context], [validity], [validation 
> attempted] and [schema specified].  In addition, such an attribute has 
> [type definition] and [member type definition] properties as 
appropriate.
> 
>      Attribute information items, as described in 2.3 of "XML 
Information 
> Set" [2], have the properties [namespace name], [local name], [prefix], 
> [normalized value], [specified], [attribute type], [references] and 
[owner 
> element].  The first two of these properties are mentioned for the 
> attribute information items described by 3.4.5 of Structures, but what 
of 
> the remaining six properties?
> 
>      The introduction of XML InfoSet Recommendation [3] states that some 

> properties may have the value unknown or the value no value, which are 
distinct from all other values.  It's not clear whether each 
> of the six properties of an attribute information item described in [2] 
> but not mentioned in [1] has the value unknown, the value no value, or 
just isn't a property of such an attribute information item.

The latter -- no such property supplied.

>      If the six absent properties aren't actually properties of such an 
> attribute information item, then I believe they should be described as 
> some other kind of information item, rather than referring to the 
> definition provided in the XML InfoSet Recommendation.

I think it's OK to be an Info Item and not have all the properties
named for that kind of Item in the Infoset REC.  There are no
'required' properties any more -- just properties whose names you
should use to supply the specified information.  Since we _can't_
supply the information named by the "missing six", we don't.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of 
Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
                     Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
                                      URL: http://www.ltg.ed.ac.uk/~ht/