In other contexts, we might not need to logically define a chemical concept as precisely as done in the previous example and only focusing on its place within the subsumption hierarchy of an ontology or taxonomy might be enough. For example, subsuming a certain kind of chemical reaction under the chemical reaction class of our hypothetical ontology, without also defining the molecular entities that have a reactant and product role in it, might suffice for our application use case. However, we still would want to provide our human users with definitions for these special kinds of chemical reactions that are as precise as possible, to make sure they can be used as intended. Using the Gold Book definition would be more straightforward in this case. If we take, for example, the Fenton reaction, we find it defined in the Gold Book as follows :