deferred node expansion question

I noticed in the note for the document-class-name property that "When 
the document class name is set to a value other than the name of the 
default document factory, the deferred node expansion feature does 
not work."  Does this mean that Xerces checks specifically for the 
class "org.apache.xerces.dom.DocumentImpl" in order to enable 
deferred node expansion, or can a custom DOM implementation extend 
from said class and still have node expansion enabled?  For instance, 
is deferred node expansion disabled if the document-class-name is 
HTMLDocumentImpl?  I'm hoping it would work in either case or, more 
generally, in any case where the custom DOM extends DocumentImpl.

Also, if anyone on the Xerces team knows anything about XMLC's 
LazyDOM, is the deferred node expansion feature equivalent to LazyDOM 
or is it something a bit different?


thanks,

Jake