Semicolons missing in use cases

The XML Query grammars (Appendix F and G, not the BNF)
include the rule that xquery units should be separated
by a semicolon.  However, the use cases whose solutions
use multiple xquery units don't take this rule into 
account.  Q12 is an one example.  It uses a function and
a query, but they are not separated by a semicolon.

- Chris Wilper