In article <38865A98.2959 at le.ac.uk>, "A.F. Simpson" <AFS7 at le.ac.uk> wrote: > Or change the system to, eg. 1,2=G 3,4=A 5,6=T. There's no 'C' in your DNA then? :) -- Richard P. Grant MA DPhil Structural Studies Group, MRC-LMB http://www2.mrc-lmb.cam.ac.uk/personal/rpg/index.html Please reply to rpg 'at' mrc-lmb.cam.ac.uk