Perl extension for managing ISO thesaurus

 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.