Why doesn't XML have Bag?

Roger L. Costello costello at mitre.org
Fri Mar 26 13:36:13 GMT 1999


Then let me ask another question - why do DTDs not allow me to specify
an unordered list of elements?  For example, 

<!ELEMENT Kitchen RDF:Bag(Sink, Stove, Refrigerator)>

With this notation I am trying to indicate that an XML document that
conforms to this DTD must have a <Kitchen> element which has three child
elements - <Sink>, <Stove>, and <Refrigerator>, and these child elements
can be in any order.  Isn't this a useful thing?  I have had a number of
times where I wish that I could do this.

I gather from your message that you are saying that it is not a
limitation of XML, but rather a limitation of DTDs?  How about DCDs? 
Thanks.  /Roger

Matthew Sergeant (EML) wrote:
> > -----Original Message-----
> > From: Roger L. Costello [SMTP:costello at mitre.org]
> >
> > Why doesn't XML support the notion of an unordered list of elements,
> > i.e., a Bag?  Perhaps this is a limitation of DTD, not XML?  That is,
> > DTDs do not support Bags, but XML has no such inherent limitation?  Does
> > DCD support Bags?  /Roger
> >
>         Unordered list in XML:
>         <ul>
>                 <li>An Item</li>
>                 <li>Another Item</li>
>         </ul>
>         Ordered list in XML:
>         <ol>
>                 <li>Item 1</li>
>                 <li>Item 2</li>
>         </ol>
>         The point is an unordered list is an application level issue, not an
> XML level issue - it's easy to implement one at your application level. Nay
> - I would go as far as to say it's trivial.
> Matt.
> --
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