- 'ps_10nestset' uses a "nested set" approach for an employee 
  hierarchy, then does arithmetic on the "salary" field;
  (soon) to be extended by inserts / deletes which imply
  mass updates on the "l"/"r" fields showing the set inclusion,
- 'ps_11bugs' will get (some of ?) those bug DB entries which
  refer to prepared statements, but whose number does not appear
  in a test file comment - so it will also be extended.