IFC, or Industry Foundation Classes, is intended to describe building and construction industry data. It is a platform neutral, open file format specification that is not controlled by a single vendor or group of vendors. It is an object-based file format with a data model developed by buildingSMART (formerly the International Alliance for Interoperability, IAI) to facilitate interoperability in the architecture, engineering and construction (AEC) industry, and is a commonly used collaboration format in Building information modeling (BIM) based projects.
IFC defines multiple file formats that may be used, supporting various encodings of the same underlying data.
- IFC-SPF is a text format defined by ISO 10303-21 ("STEP-File"), where each line typically consists of a single object record, and having file extension ".ifc". This is the most widely used IFC format, having the advantage of compact size yet readable text.
- IFC-XML is an XML format defined by ISO 10303-28 ("STEP-XML"), having file extension ".ifcXML". This format is suitable for interoperability with XML tools and exchanging partial building models. Due to the large size of typical building models, this format is less common in practice.
- IFC-ZIP is a ZIP compressed format consisting of an embedded IFC-SPF file or IFC-XML file and having file extension ".ifcZIP".
Files begin with signature bytes "ISO-10303-21". It can be also identified by file schema "IFC2X3".