The Exact search type, also known as an Identity search, is intended for use when you must know if a perfectly identical copy of your query compound is present in the database. The target must be chemically identical to the query, including stereochemistry, charges, and isotopy. It is a convenient shorthand for full structure, same-stereochemistry, and appropriate settings of all the other options. Thus, generic atom and bond types such as R, A, and Double-or-Aromatic in the query will match corresponding atom and bond types in the target only if they are also of the same generic type. In other words, an atom labeled “R” in the query must find a matching atom labeled “R” in the target to produce a hit. If the stereochemistry of the query is unspecified, it will only hit targets which do not specify stereochemistry. The only variable in an exact match search is whether or not it is tautomerically flexible.