XSD: Proposed Goals, Rev. 3

Paul Prescod papresco at technologist.com
Fri May 29 03:47:10 BST 1998

On 28 May 1998, Lars Marius Garshol wrote:

> I think you should keep the original wording:
>     9. XSD shall include mechanisms for extending the information
>     included in SDDs.
> IMHO this is a very important part of the whole thing because it gives
> us a way to put constraint information in the document definition.
> Like Paul says, this can be abused, but I think the benefits are
> persuasive.

My problem is that I can't differentiate an abuse from a proper use. Any
extension is going to cause backwards compatibility problems, just as HTML
extensions do. The only way to manage extension is with layering and

> If the bar attribute of the foo element can only contain numbers
> between 5 and 10 I want to keep that information in my document
> definition, and not buried in the 14 different scripts that work on
> these documents.

As I pointed out, we can allow extension without defining an extension 
mechanism that can change the definition of verification, just as XML
allows extensions that do not change the definition of "well-formed" or 

 Paul Prescod

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