ascending
descending
empty greatest
empty least
collation "name"
<bib>
 {
   for $b in doc("bib.xml")//book[publisher = "Addison-Wesley"]
   order by ($b/title) descending
   return
    <book>
     { $b/@year } { $b/title }
    </book> 
 }
</bib>Adapted from XML Query Use Cases