The crystal structure of UoB-100(Dy) is highly disordered, as can be derived from the many partially occupied atom sites in the average structure refinement [Fig. ]. We interpret the crystal structure by first considering the metal-containing secondary building unit (SBU), which is centered around the 1b Wyckoff site (D6h point symmetry). There are two symmetry-distinct Dy sites: 12o and 6m. Thus, there are 18 Dy atoms per SBU in total, although each of which has an occupancy of 0.5. This probability indicates that each SBU in the real structure contains 9 Dy atoms. In principle, there are C(18, 9) = 48620 possible nodes with this correct number of Dy atoms. However, on closer inspection, only two of these configurations are chemically feasible: the closest contact between the nearest 12o Dy sites is 2.21 Å and the closest contact between 12o and 6m Dy sites is 2.66 Å. We reason that it is unlikely that pairs of Dy atoms are separated by such short distances and therefore exclude node geometries that include these small separations. Only two configurations satisfy these local rules, as shown in Figure ). We will go on to show experimentally that these nonanuclear clusters indeed exist in the local structure.