XQuery Usecase "PART" incorrect?

Hello,
I've stumbled across a little incorrectness in the use cases (I believe). This is from the source of PARTS Q1, line #15:
    for $p in doc("partlist.xml")//part[empty(@partof)]
                                        ^^^^^
Whereas in the main XQuery Specification "empty" stands in the list of reserved function names. So the built-in function "empty" may (or at least should) not be called without using a proper prefix like in the functions and operators spec: "fn:empty()". It's a minor thing but should be corrected in the use cases as it might not be too obvious to users.

mfg
Martin Probst