A thesaurus is a classification structure. it can be seen as a graph where nodes are terms and the vertices are relations between terms.

biblio::thesaurus provides transparent methods to maintain thesaurus files. the module uses a subset from iso 2788 which defines some standard features to be found on thesaurus files. this iso includes a set of relations that can be seen as standard but, this program can use user defined ones. so, it can be used on iso or not iso thesaurus files.