A correspondence table is a tool for the linking of statistical classifications. A correspondence table systematically explains where, and to what extent, the categories in one classification may be found in other classifications, or in earlier versions of the same classification.
Methodologically, correspondence tables describe the way in which the value sets of classifications are related, by describing how the units classified to the groups defined for one classification would be classified in other classifications. However, a one-to-one link between versions might not always be possible, or only for a limited number of codes of the classification and/or at a more aggregated level.
A correspondence table is a conceptual mapping between classifications, while a bridge coding is a numerical mapping between classifications.