Hi, I am trying to sort out some issues with the constrained occupancy refinement in phenix 1.4.3. The structure I am working on is fairly high resolution ~1.4A and it looks as if a couple of the alternative conformations would benefit from occupancy refinement, no hydrogens are present yet. I defined the constrained groups like this: occupancies { individual = None remove_selection = None constrained_group { selection = chain A and resid 66 and altid A selection = chain A and resid 66 and altid B } .... I expected that the sum of occupancies would be restrained to 1, which they should according to the manual, but the refinement gives me occupancies of 0.7 for altid A and 0.34 for altid B, starting values were both 0.5. Similar discrepancies were also present in other groups, like 0.5 A, 0.37 B etc. The latter is the largest deviation from 1 I have seen in thus far. The alternate conformations were generated in coot, by splitting at the CA position. Is this a rounding error I just have to contend with or is there some other parameter I need to tweak? Cheers, Carsten