However, a full molecular specification of a reaction will often include more molecular details. One of them is the "atom-atom mapping" (AAM), which is to say which atoms from the reactants correspond with which atoms in the products. Then there is also the reaction center about which we may have information describing the detailed reaction mechanism. For example, a nucleophile attack by a negatively charged oxygen moiety on a partially positive charged C-atom whose electron is pulled by an electronegative halogen. These reaction mechanisms may be depicted with dashed and dotted pseudo bonds and arrows, in some cases conformation shifts may be depicted by multiple reaction center models as in a comic. In enzymatic reactions the structure of the reaction center and conformation shifts of the enzyme are often of great interest and might be detailed in 3D structures.