Headings related hierarchically are connected by means of reciprocal BT (Broader term) and NT (Narrower term) references. A heading is linked to the level immediately above it and the level immediately below it in the appropriate hierarchy. Types of hierarchical relationships include Genus/species (or class/class member), Whole/part, and Instance (or generic topic/proper name example).

10.2 References

10.21 Broader terms

10.22 Narrower terms

See also:

10.0 Term relationships