I don't know what does 'certified' mean. My original question was to make sure RHEL4 64bit is the right one to use. And I think we still have this issue of RHEL vs SLC. I will e-mail Fred and David to get more info. Wei Yang | [log in to unmask] | 650-926-3338(O) Young, Charles C. wrote: > I wonder what it means to certify. Results are the same? Results are the > same _and_ CPU performance is no worse? Results are the same, CPU > performance is no worse and memory requirements are similar? Anyone > know? > > -- > Charles C. Young > M.S. 43, Stanford Linear Accelerator Center > P.O. Box 20450 > Stanford, CA 94309 > [log in to unmask] > voice (650) 926 2669 > fax (650) 926 2923 > CERN GSM +41 76 487 2069