Comments on Section 2.6 of XML-Namespaces

Andrew n marshall amarshal at usc.edu
Wed Apr 1 10:44:02 BST 1998


On Tuesday, March 31, 1998 7:26 PM, Andrew Layman 
[SMTP:andrewl at microsoft.com] wrote:
> Thanks for your question, and for reading the document closely.
>
> I think you are expecting namespaces to do more than it in fact does.
> Namespaces simply allows you to distinguish the T.Heat:Temp attribute 
from
> the T.Color.Temp attribute.  It does not take on the job of expressing
> grammatical rules such as that the T.Heat.Temp attribute must only be 
used
> in conjunction with another attribute, e.g. T.Heat.Units.  Namespaces are
> just a named set of names.  Keeping the names distinct is the goal of
> namespaces.  Defining the grammar, semantics, etc. of the named things is
> beyond the pale.

But aren't attribute names already unique?  From the XML spec [3.3], a DTD 
may contain "at most one attribute definition for a given attribute name 
[in an attribute-list declaration]".  As long as the element names unique, 
which it seems you have done successfully, then there is no need for your 
syntax.  I believe the syntax you propose introduces more problems than it 
is worth for the previously given reasons, even if it does not intend to 
describe semantics.

I will make one exception, which it seems you are already aware of: 
processor specific information that may apply to every element and 
therefore does not specify a particular element as the source of the 
attribute.  A good example of this usage can be found in the new XLink 
notation 'xml:link'.  Another possible use may be in XML architectures, as 
in 'Arc:URL' ( realize this isn't the currently recommended form, but I 
think it makes sense).

I guess my complaint boils down to allowing QNames of the form 
'namespace:ELEMENT.attribute' as the name of an Attribute.  While I don't 
see any reason for this notation at all, it should at least include a 
validation constraint to check that the STag uses the QName 
'namespace.ELEMENT'.

Andrew n marshall
  student - artist - programmer
    http://www.media-electronica.com/anm-bin/anm
      "Everyone a mentor,  Everyone a pupil"

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