Hi All, I have a dataset of 17 .CEL files, i want to find out all the probes (PM and MM) common to all 17 .CEL files which fall in the range 200 to 20000. Affymetrix makes 11-16 probes/gene, some probes ID's from the 11-16 will satisfy the criteria in the same .CEL file and also in other, shown below is the example, now how do i make sure that 1282 in sample one has the same position as in sample 2. Example: PM MM PM MM 1282_s_at 902 2847.5 3064 1358 1282_s_at 597 1570 1796 803.5 1282_s_at 491 1380.8 935.5 611 1288_s_at 2913 5054 4965.3 3027.3 1288_s_at 6344 10731.8 11410.5 7839.8 Also can one access sequence data for the probes? Please help. Thanks, Hrishi