The IFC-data-schema is modelled and specified with ISO-STEP-Technology (EXPRESS modelling language, STEP-Physical File Exchange Format (SPF)). In Addition there is also an XML-specification available, which is semantically identical with the EXPRESS-specification. Most implementers are using STEP-compliant toolboxes or databases for the implementation of their IFC-interface. A toolbox provides an API towards the application and on the other side reads/writes the IFC-file and/or connects to a database. Some toolboxes are supporting only SPF others SPF and XML, so that an implementer doesn't has to take care about these technical details and can deliver what his customer demands.

Several IFC-releases had been published since the start of IAI in 1996. With IFC2x a new so called "platform-concept" had been introduced. Based on this concept it is easier to extend the IFC-model for specifc application domains, without the need to change the core. Due to this concept upward compatibility is easier to implement and up to a certain extend also downward compatibility. However, upward compatibility is not guaranteed automatically through the model, but requires specifc care through the implementer of an IFC interface.

Most recent release:

• IFC2x3 (earlier called "IFC2x2 Addendum 2", pre-releases were available since summer 2005 in the virtual workspace "ISG-Workspace 2006", the final release was published through IAI International Website, on 21 Feb 2006)
  • Details on virtual workspaces
• Pilot-implementations in 2005 helped to stabilize and bugfix IFC2x3 so that it has reached a mature status.
• IFC2x3 is now recommended to be used for implementation
• Guidelines are available in the virtual workspace "ISG-Workspace 2006"
• Currently beeing implemented by many software application developers. IFC2x3 turns out to be a new meeting-point for several applications supporting various, but not always the same IFC-releases.
• A certification-program for IFC2x3 is defined and started
  • The view-definitions for the certifications are also available in the "ISG-Workspace 2006"

Earlier IFC releases based on IFC-platform concept:

• IFC2x2 Addendum 1
• IFC2x2
• IFC2x Addendum 1 
• IFC2x

Earlier IFC releases based on initial IFC-model concept (meanwhile out of date): 

• IFC2.0
• IFC1.5.1
• IFC1.5
• IFC0.98 (prototype)

Specifications of actual and recent releases are available on:

IAI International Website