This inventory contains a set of terms that are relevant to the study of medical history.
The inventory is organised as a set of "heading terms", belonging to one of seven different semantic categories, each of which is accompanied by a set of semantically-related terms. There are around 175,000 heading terms.
The nature of the semantic relationship holding between the heading term and each related term varies. A pair of related terms may, for example be synonyms of each other, one term may be more or less specific than the other, one may be a part of the other, one may be used in the treatment of the other, etc.