Catalogs put much less focus on the instance's construction.

Example:

<e:event xmlns:e="http://www.milowski.com/schemas/example-form/event/200402">
...
</e:event>

and the catalog has the mapping information:

<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog" prefer='public'>   
<uri name="http://www.milowski.com/schemas/example-form/event/200402" 
     uri="event.xsd"/>
</catalog>