This looks like a paper to me. I'd humbly suggest that you visit your library. You know, the place where they keep the books. -- Richard P. Grant University of Oxford Nuffield Department of Obstetrics and Gynaecology http://users.ox.ac.uk/~lady0266 http://www.molbiol.ox.ac.uk/~rgrant Splat thwick McSpladge! All over me nadgers!