FIG. . Union of all bond environments using the T ‡ mapper, resulting in a branched SMARTS. The branched SMARTS is used to determine how to extend the chemical environment of a parameter SMARTS. If a parameter matches the two atoms in the blue edge, then the chemical environment can be extended using nodes connected by the orange edges, where the SMARTS information of the new node in the parameter will be the union of the 3 orange nodes since they have isomorphic graph topology. See text for details on this process (Sec. III B).