One challenge with this approach is that isotopically-labeled mechanisms grow exponentially with the number of atoms that can be isotopically labeled. For example, a single asymmetric molecule with six carbons would be represented by 64 different species with various carbon atoms enriched. Despite the combinatorial complexity, this method is still very useful for generating detailed isotopic mechanisms, and has been shown to provide good agreement and insight into position-specific isotope analysis experiments. Currently, the algorithm is limited to generation of isotopic mechanisms for C, though the framework is easily extensible to other isotopes.