Finally, the atomic descriptors are constructed for the identified atomic sites by creating and concatenating shells of neighboring atoms around the query atom, including atoms up to three bonds away. The shells contain calculated CM5 atomic charges sorted according to a modified version of the Cahn-Ingold-Prelog (CIP) priority rules; modifications include summing atomic numbers rather than comparing sorted lists of atomic numbers, and disregarding bond orders. Compared to our previous work, we have re-implemented the sorting algorithm to comply with the following priority rules: