ambiguity in RDF/XML bnode short form?

I'm reading 
http://www.w3.org/TR/rdf-syntax-grammar/#section-Syntax-property-attributes-on-property-element 
, which says that instead of,

<rdf:Description>
  <ex:editor>
    <rdf:Description ex:fullName="Dave Beckett" />
  </ex:editor>
</rdf:Description>

I can use,

<rdf:Description>
  <ex:editor ex:fullName="Dave Beckett" />
</rdf:Description>

There seems to be no qualification that the bnode object must have at 
least one property. From the text, then, I should be able to replace,

<rdf:Description>
  <ex:editor>
    <rdf:Description/>
  </ex:editor>
</rdf:Description>

with

<rdf:Description>
  <ex:editor/>
</rdf:Description>

This is ambiguous with the same syntax for a plain literal object, as 
the following produces an identical info set:

<rdf:Description>
  <ex:editor></ex:editor>
</rdf:Description>

What am I missing here? Shouldn't there be a qualification at 
http://www.w3.org/TR/rdf-syntax-grammar/#section-Syntax-property-attributes-on-property-element 
that restricts the short form to bnodes with at least one property?

("If all of the property elements on a blank node element..." doesn't 
seem to be sufficient qualification, as "all of" applies to zero 
instances just as well as to 20 instances.)

Garret