bitand SQL operator

Hello all,
  I recently came across the bitand sql operator and I was wondering if anybody out there could supply some more information on it. As far as I can tell its for testing whether certain binary digits are set or not I've experimented with it using this presumtion but have had mixed results.

  So if anybody does know how it works or where I can find out more I'd be most grateful if you'd let me know.

Cheers,

Jon.

-- 
Jonathan M. Whitehead           | j.m.whitehead_at_sheffield.ac.uk
Dept. Of Corporate Information  | 
University Of Sheffield         |
Firth Court                     |
Western Bank                    |
Sheffield                       |