A thesaurus is structured like a network of nodes linked together by relations. Net Search Extender looks up a term in a thesaurus by starting at the term, then following a path through the term relations and delivering the terms found in the process.
Figure 28. An example of the structure of a thesaurus
Thesaurus entries are connected by relations. Relation names, such as BROADER, let you restrict an expansion to certain named lines in the relation hierarchy. Some relations are bidirectional, others are unidirectional; BROADER, for example, is the name of a unidirectional relation.