International Standards for Information Modelling
501(c)(3) The language family
behind smart manufacturing
The EXPRESS Language Foundation maintains and promotes the ISO 10303 language family — powering industrial data exchange, interoperability, and digital twins since 1982.
5
Languages
40+
Years of history
ISO
10303 Standard
SCHEMA Part_Management;
ENTITY part;
id : STRING;
material : REAL;
mass : MEASURE_VALUE;
END_ENTITY;
END_SCHEMA;Language Family
Five languages, one standard
Each language serves a distinct purpose in the information modelling lifecycle.
EXPRESS
The core data modelling language — entities, types, constraints, and rules for defining information schemas.
ISO 10303-11
EXPRESS-G
Graphical notation for EXPRESS — entity-relationship diagrams for visual data modelling.
ISO 10303-11
EXPRESS-I
Instance definition language for populated data models and conformance testing.
ISO 10303-12
EXPRESS-X
Schema mapping language for defining transformations between different EXPRESS data models.
ISO 10303-14
EXPRESS-Q
Query language for defining mappings between ARM and MIM schemas with reference path syntax.
ELF Specification
History
Four decades of innovation
EXPRESS conceived during the PDDI program at McDonnell Aircraft
Proposed as an International Standard at ISO by NBS (now NIST)
ISO 10303-11 published by Schenck & Wenzel; reference manual by Schenck & Wilson
EXPRESS Edition 2 (ISO 10303-11:2004) with Loffredo & Wilson
EXPRESS Language Foundation established as a 501(c)(3) public charity
Heritage
Born from industry leaders
The EXPRESS language originated from collaboration between major aerospace, manufacturing, and standards organizations.
Latest News
From the foundation
Thoughts on EXPRESS
Personal thoughts from inventor of EXPRESS, Douglas Schenck, on the origin and hopes of EXPRESS.
Douglas Schenck
EXPRESS Language Foundation joins the Metaverse Standards Forum as Principal
The EXPRESS Language Foundation has joined the Metaverse Standards Forum as a Principal and founding member to enable semantic interoperability in the metaverse.
Thomas Thurman
A history of the EXPRESS languages
The official account of EXPRESS history, by its founders!
Douglas Schenck, Peter Wilson, Bernd Wenzel
Learning Resources
Get started with EXPRESS
EXPRESS Language Reference Course
The authoritative course on the EXPRESS language from its co-inventor — syntax, semantics, modelling patterns, and practical exercises.
By Peter Wilson, co-author of Information Modelling: The EXPRESS Way
Start learningEXPRESS & STEP in Practice
The applied course on the ISO 10303 ecosystem — STEP file formats, data validation, schema querying, SDAI programming, and PLCS.
Contributed by Jotne EPM Technology
Explore courseJoin the EXPRESS Language Foundation
We facilitate education, standardization, research, and promotion of the EXPRESS language family. Membership is open to organizations and individuals worldwide.
Founded by the original inventors of EXPRESS, including Douglas Schenck, Peter Wilson, and Allison Barnard Feeney.
ELF is a US-registered 501(c)(3) public charity.