rot is a high-probability labeled configuration, all the N perm labeled configurations obtained by permuting positions of identical particles also have high (namely, the same) probability. Therefore, given a certain high-probability region of ρ nuc,rot , there are a total of N perm high-probability regions that can be obtained by applying permutation operators. However, these need not all be unique. If after application of a permutation one obtains Figure : a) Illustration of the concepts "coordinate vector", "labeled configuration", and "unlabeled configuration" for molecules with the chemical formula C 2 H 6 O. For coordinate vectors, positions of identical nuclei are labeled and the molecule is oriented with respect to a coordinate frame. For labeled configurations, orientation in space is irrelevant, and for unlabeled configurations also the labels on positions of identical particles are removed. b) Relationships between the three concepts.