Check out: http://www.csd.abdn.ac.uk/~tnorman/teaching/CS1016/lectures/abdn.only/lecture1.pdf Slide 10. Must be viewed from inside the University proxy. You don't get better publicity than that. (: Regards, Iain Learmonth Head of IT Computing Science Society University of Aberdeen e: adapa@xxxxxxxxxxxx t: +44 (7853) 027574