Figure 2.

A model for CHISL (Categorical Health Information Structured Lexicon) concept. The concept ‘Chest Pain History or Symptom’ is modeled in CHISL with a preferred synonym ‘Chest Pain’. Chest Pain may be set to absent or present (with ‘absent’ the explicitly defined normal status) and can be modified, including severity, chest pain quality, chest pain radiation, chest pain-associated conditions, among others not listed here. The arrows represent references from the concept to its modifiers. This figure is only reproduced in colour in the online version.