Note that since one compound may occur in more than one pathway class, the sum of the compounds over the 11 pathway classes in Group-I turns out to be 4,860, which is greater than 4,366. Likewise, the sum of the compounds over the 11 pathway classes in Group-II is 3,606, which is greater than 3,137. This is quite similar to the case of proteins with multiple location sites, as elaborated in [24, 25] .