Figure 1.

Two approaches to composing the concept “severe chest pain.” (Top) A user selects concepts and modifiers directly from a reference terminology permitting post-coordination, using description logic to combine unrelated atomic concepts sequentially, starting with “pain,” then adding the location modifier “chest” and the severity modifier “severe.” (Bottom) The user can combine the pre-coordinated concept “chest pain” in an interface terminology with the formally linked modifier “severe” from the list of chest pain modifiers. All concepts and modifiers in the interface terminology are mapped to formal representations in an external reference terminology. Both approaches allow the user to compose a meaningful concept having a formal representation.