Major versus minor descriptors

Major versus minor descriptors
A major descriptor is a descriptor in a bibliographic record representing a main subject of the document indexed, usually indicated by an asterisk or other symbol or distinguished typographically. Minor descriptors, on the other hand, are descriptors representing less significant aspects of the contents (left unmarked to be distinguishable from major descriptors).

Some databases such as ERIC on Dialog allows searcher to limit searches to major descriptors (for higher precision) or to search both major and minor descriptors (for higher recall). Minor descriptors thus contribute to greater exhaustivity in indexing. This differentiation is also a primitive form of index term weighting.