ISO/IEC/IEEE 31320-2:2012 describes the semantics and syntax of IDEF1X, a language used to represent a conceptual schema. Two styles of IDEF1X model are described.

1. The key style is used to produce information models that represent the structure and semantics of data within an enterprise and is backward-compatible with the US government's Federal Information Processing Standard (FIPS) PUB 184, Integration Definition for Information Modeling (IDEF1X).
2. The identity style is used to produce object models that represent the knowledge, behaviour, and rules of the concepts within an enterprise. It can be used as a growth path for key-style models. The identity style can, with suitable automation support, be used to develop a model that is an executable prototype of the target object-oriented system.