ISO 10303-11:2004

Overview

ISO 10303-11:2004 - "Industrial automation systems and integration - Product data representation and exchange - Part 11" - is the EXPRESS language reference manual. It defines EXPRESS, a formal data specification language for unambiguous product data definition and constraint specification, and it also specifies EXPRESS‑G, a graphical representation for a subset of EXPRESS constructs. The part focuses on the language elements needed to define data types and constraints on instances; it is explicitly not a programming language and does not define database, file or transfer formats, process control, information processing or exception handling.

Key Topics

The standard covers the full EXPRESS language reference and related syntax and semantics. Major technical topics include:

• Basic language elements: character set, reserved words, identifiers, literals
• Data types: simple types (integer, real, string, logical), aggregation types (array, list, bag, set), named and constructed types (entity, defined types, enumeration, select)
• Declarations: types, entities, attributes, constants, schemas, and specialization/subtyping rules
• Constraints and rules: local and global rules, subtype constraints, value uniqueness and coverage constraints
• Expressions and operators: arithmetic, relational, logical, string and aggregate operators; query expressions and indexing
• Executable constructs: functions, procedures, control statements (if, repeat, case, return) used within EXPRESS algorithms
• Scope, visibility and interfaces: schema interfaces, use/reference interaction and implicit interfaces
• Graphical notation: EXPRESS‑G diagrams for visualizing selected EXPRESS constructs
• Conformance and implementation considerations: language parser and graphical editing tool guidance (conformance requirements)

Applications

ISO 10303-11:2004 is used by organizations and professionals who need precise, machine‑readable product data definitions:

• Data modelers and schema authors creating formal product information models
• CAD/CAM/PDM integrators defining interoperable product data schemas and validating data constraints
• Tool vendors and implementers building EXPRESS parsers, validators and graphical editors (EXPRESS‑G support)
• Systems engineers and standards developers who require unambiguous data specifications for product lifecycle integration
  Practical benefits include consistent data interchange semantics, enforceable constraints for data quality, and a basis for interoperable product data representations.

Related Standards

• ISO 10303 series (other parts that define applications and protocols)
• ISO 10303‑1 (concepts referenced by EXPRESS)
• ISO/IEC 10646 (character set / terminology references)

Keywords: ISO 10303-11:2004, EXPRESS language, EXPRESS‑G, product data representation, data specification language, data types, schema, constraints, product data exchange.