IFC STEP Physical File Syntax

The .ifc file is a STEP Physical File (SPF, also called Part 21 or p21), governed by ISO 10303-21. It is a clear-text encoding in which each entity instance is a line and attribute values are an ordered sequence of unnamed values. This skill covers the file skeleton, the HEADER section, the DATA section instance syntax, value notation, string escaping, and the ifcZIP container.

Verified against the buildingSMART IFC formats documentation, the IFC Header Data Implementation Guide v1.0.2, the ifcZIP implementation agreement CV-2x3-154, and ISO 10303-21. Applies to IFC2x3, IFC4, IFC4.3: the SPF syntax is identical across all three; only the FILE_SCHEMA identifier and the entity set differ.

Quick Reference

The file skeleton