Hello, I fetched entry EMD-2463 from EMDB and issued: measure symmetry #0 nMax 24 and got the result "Symmetry emd_2463.map: C13, center 64 64 37" Increasing the number of sampling points does not change the result, but if I increase the correlation criteria a little, to say 0.992, I get the expected C12 symmetry. Also if I change the contour level to 0.05, the author recommended level, I get C12 again. Looking at the volume at several different contour levels, it is difficult to see how it could be considered C13, and also how it would go from C13 to C12. Kind Regards, Ingvar Lagerstedt -- Ingvar Lagerstedt European Bioinformatics Institute (EMBL-EBI) European Molecular Biology Laboratory Wellcome Trust Genome Campus Hinxton Cambridge CB10 1SD Tel: +44 (0)1223 492533