My previous posting did not get answer, it might be a bit confusing. My questions is if I want to conbine phases from three different sources, 2 MAD data sets and a partial model, can I run SIGMAA twice? Combining MAD phases first, and then add in the model phases to the pre-combined MAD phases. When I run SIGMAA the second time CCP4i GUI allows me to choose labels PHCMB, HLAC, HLBC, HLCC, HLDC, but doesn't let me use WCMB as the input FOM. Is this a bug in the GUI or SIGMAA simply does not allow to use WCMB as an input FOM? Thanks in advance. Huiying ------------------------------------------------- Huiying Li, Ph. D Department of Molecular Biology and Biochemistry Natural Sciences I, Rm 2443 University of California at Irvine Irvine, CA 92697, USA Tel: 949-824-4322(or -1953); Fax: 949-824-3280 email: [log in to unmask] --------------------------------------------------