Rule 6 also allows assignment of stereodescriptors for centers with axial symmetry, such as those involving allenes and biphenyls. No further special consideration of high-symmetry compounds or groups is necessary. Interestingly, an easy extension of Rule 6 solves the heretofore unresolved issue of "in/out" stereochemistry such as shown in Figure . These compounds can be treated successfully simply by taking into account the temporary re-assignment of auxiliary descriptors after each promotion of a node. However, we stop short of recommending this modification at this time, as it only applies to rather esoteric structures mostly of only theoretical interest. Its implementation would result in additional (unnecessary) descriptors for common all-r "all-out" structures, many of which are known compounds and have already been arbitrarily assumed to have no stereodescriptors.