Table 2.

 COSTART hierarchical structure^{8 9}

No of terms	Level of term	Example
12	Body system	Nervous system
	Mid-level classification	Depression
About 1200	Coding symbol (analogous to preferred term)	Depression
>6000	Glossary terms (used to assist in selection of coding symbol, analogous to lowest level terms of MedDRA)	Suicidal tendency, depression agitated, depression mental, melancholia, depression worsened, depressed reaction, oppression, dejection emotional, moroseness, depression reactive, dysphoria, depression aggravated, depression functional, depression psychic, depression neurotic, anhedonia, depressed state

COSTART=Coding Symbols for a Thesaurus of Adverse Reaction Terms.

Examples using http://bioportal.bioontology.org/ontologies/COSTART.