Hi Gordon, For Imagene output on Amersham Codelink files for the 20K UniSet Human I chip, I know the ranges of the spot coordinates are: Field metarow metacol row col B 1 1 1:5 1:71 A 1 1:8 1:154 1:8 C 1 1 1:5 1:71 B1 1 1 1:5 1:71 A1 1 1:8 1:154 1:8 C1 1 1 1:5 1:71 where the order of the Fields in this list is how they are laid out on the array. Also, the spots are laid down in a hexagonal packing arrangement. There is a 55K Human chip that will be available soon, but I don't know what the imagene output file will look like as far as the fields and such. Hope this is helpful, Dick ********************************************************************** ********* Richard P. Beyer, Ph.D. University of Washington Tel.:(206) 616 7378 Env. & Occ. Health Sci. , Box 354695 Fax: (206) 685 4696 4225 Roosevelt Way NE, # 100 Seattle, WA 98105-6099 http://depts.washington.edu/ceeh/ServiceCores/FC5/FC5.html