Re: 3rd try on versioning question

Hi Tony,

Thanks for the informative answer.  One comment.

> The other problem with not versioning namespaces is that the XML 
> Schema spec itself suggests that applications can select the Schema to 
> validate a message with based solely on the namespace URI.  That 
> pretty much forces you to put version information in the namespace URI 
> for most applications.  If the world was different, and the Schema 
> spec provided support for selecting a Schema based on the namespace 
> URI *and* one or more attributes on the top-level element, it would be 
> different.  That isn't the case, and so versioning the namespace URI 
> seems to be the way forward if you are doing something other than 
> (X)HTML.

XML Schema does provide a place that could be used for version 
indicator: schemaLocation.  The location URI is a hint for the 
processor -- seems like a processor could use it as a versioning hint.

<p:message xmlns:p="ns" xsi:schemaLocation="ns v2.1" .../>

That's a bit of a hack, but workable if adopted by a group of parties 
sharing XML and XML Schemas.  And it suggests a possibility for a 
future version of XML Schema:

<p:message xmlns:p="ns" xsi:schemaVersion="ns v2.1" .../>

<xs:schema targetNamespace="ns" schemaVersion="v2.1" .../>

xan