Supported ITS layouts. (top) ITS layouts found within the elementary reaction data set from . The number within the vertices corresponds to atomic oxidation state changes, broken bonds are dotted given a negative bond label while formed bonds show positive numbers. (left) Homovalent elementary reactions result in even sized cycles with no oxidation state changes at the atoms (see Figure 1). (middle) Odd cycles with two oppositely charged atoms separated by a non-changing pseudo bond (dashed edge labeled 0 see Figure 5). (right) Similar layout involving two equivalent oxidation state changes. Note, the inverse layout was also found and used. (bottom) Additionally supported ITS layouts for ambivalent elementary reactions involving non bonding electrons. These result in odd sized cycles and oxidation state changes of one atom. Note that this situation is equivalent to a non-elementary cycle with alternating bond labeling (middle).