# Archetype Definition Language

**Abbreviation:** ADL
**Definition: **ADL is a formal language for expressing archetypes. It provides a formal, textual syntax for describing constraints on any domain entity whose data is described by an information model (also known as the 'underlying reference model'). The ADL syntax is semantically equivalent to the AOM, and represents one possible serialisation of the AOM. The current version of ADL is known as 'ADL 1.5'.

**Reference Definition:** ADL is a formal language for expressing archetypes. It provides a formal, textual syntax for describing constraints on any domain entity whose data is described by an information model (also known as the 'underlying reference model'). The ADL syntax is semantically equivalent to the AOM, and represents one possible serialisation of the AOM. The current version of ADL is known as 'ADL 1.5'. (**openEHR Foundation website)**
**Instance of:** Formal Language
**Instance of:** Clinical Modelling Language
**Instance of:** Standard or Specification