[bdbxml] Query to retrieve all container content?

Can anyone tell me if there's a generic XQuery that will return me all
the XML content in a container without having to specify element names?
 
e.g. collection('sample.dbxml')// (doesn't work)
 
I could use a FLWOR expressions such as:
 
for $i in collection('Sample.bdbxml')/publication return $i
 
but I don't want to have to supply the /publication element. This is
because we may not know what the XML document structures are in the
container.
 
Thanks,
Ant