OASIS catalogs: <system> and <uri> entries

In Saxon 9.4 we have introduced built-in support for XML catalogs (about 
time, I hear you say...)

I have noticed that some catalogs for collections of schema documents, 
for example DITA, have entries like this:

<system systemId="urn:oasis:names:tc:dita:xsd:map.xsd:1.1" uri="map.xsd"/>

These aren't working with the Saxon 9.4 schema processor, which is 
instead looking for an entry of the form

<uri name="urn:oasis:names:tc:dita:xsd:map.xsd:1.1" uri="map.xsd"/>

This is because Saxon uses a URIResolver for deferencing the URI, and in 
the OASIS catalogResolver, the URIResolver implementation looks for 
<uri> entries, whereas the EntityResolver implementation looks for 
<system> entries.

Am I right in thinking that

(a) there's nothing really in the specs to justify the convention of 
using <system> rather than <uri> for this purpose

(b) nevertheless, it is established practice, and therefore

(c) the Saxon schema processor ought to work this way?

Michael Kay
Saxonica