Null HTMLDocument domain?

Hello,

I'm currently investigating some null vs. empty string issue in
Konqueror's DOM implementation and its ECMAScript bindings. From reading
the spec I can't really see a clear line and have to rely on an
trial&error approach by comparing the results to other implementations.

I'd like to pick one example and kindly ask for some feedback on how to
treat this issue: The "domain" property of HTMLDocument is specified as

 "The domain name of the server that served the document, or null if the
  server cannot be identified by a domain name."

When would this ever null? If the document is located under a file:// URL
for example? None of the ECMAScript bindings I tested ever returns null,
though. Even the DOM TS tests for "" instead of the null ECMAScript value
in HTMLDocument03.html.

Thanks,

Harri.