Abstract A searcher in a list of phrases which serves as an index to a set of documents often has problems finding the right words when the information sought for has to be described. Offering alternative phrasings and pointing to related concepts in the index could be a great help in this difficult process of query formulation. Usually the index is obtained by characterizing the set of documents. This paper examines the effect of adding semantic relations to the index. Various ways in which nodes in an index can be related are discussed, and criteria for adding new index entries are introduced. The effects of adding relations on the process of offering support during the formulation process are treated as well.