Hi I have an unexpected result, my syntax must be incorrect. The relevant script commands are below, the problem is residues A113 and B143 have alternate conformation occupancies that sums to 0.98 to 1.06 respectively. Clearly alternate conformations of a single residue should sum to 1 (or less than 1 possibly). Any suggestions please? Thank you, Mark refine { strategy = *individual_sites \ rigid_body \ *individual_adp \ group_adp \ tls \ individual_occupancies \ *group_occupancies \ group_anomalous \ occupancies { individual = None group = chain A and resid 113 and altid A group = chain A and resid 113 and altid B group = chain B and resid 143 and altid A group = chain B and resid 143 and altid B } }