Core dictionary (coreCIF) version 2.4.5
The fraction of the atom type present at this site. The sum of the occupancies of all the atom types at this site may not significantly exceed 1.0 unless it is a dummy site. The value must lie in the 99.97% Gaussian confidence interval -3u =< x =< 1 + 3u. The _enumeration_range of 0.0:1.0 is thus correctly interpreted as meaning (0.0 - 3u) =< x =< (1.0 + 3u).
Appears in list containing _atom_site_label
The permitted range is 0.0 -> 1.0
Enumeration default: 1.0