[F&O] IBM-FO-023: Example inconsistent with text

(IBM-FO-023): In Section 7.5.4, fn:substring-before(), paragraph 3 says 
that if $arg2 is the zero-length string, the function returns the 
zero-length string. But the example in the second bullet has a zero-length 
$arg2 and it does not return the zero-length string. Is this a bug in the 
example?

--Don Chamberlin