Why doesn't XML have Bag?

[Frank Boumphrey]

In SGML you can put
(a&b&c) whicch means that eachelement must appear only once but in any
order.

The best you can do in XML (without getting rediculosly complicatedis

(a|b|c)* which means that they can appear in any order, but there can be any
number of them

My understanding was that it was ommited because of the requirement

"XML software shall be easy to write"

It takes only a few lines of C code to validate the second requirement but a
LOT more to validate the first.

Frank
----- Original Message -----
From: Roger L. Costello <costello at mitre.org>
To: <xml-dev at ic.ac.uk>
Cc: <alk at mitre.org>; Roger Costello <costello at mitre.org>
Sent: Friday, March 26, 1999 6:59 AM
Subject: Why doesn't XML have Bag?


>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
>
>
>xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
>Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on
CD-ROM/ISBN 981-02-3594-1
>To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
>(un)subscribe xml-dev
>To subscribe to the digests, mailto:majordomo at ic.ac.uk the following
message;
>subscribe xml-dev-digest
>List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)
>
>


xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)