Based on established, international standards for common objects in the building industry, the Industry Foundation Classes (IFC) file format provides an interoperability solution between different software applications.
Using the IFC format, you can export drawings to other IFC-certified applications that could not otherwise open a DWG file. Likewise, you can import an IFC file to create and work in a DWG that was originally created in a format other than DWG.
For more detailed information about IFC, go to http://www.buildingsmart.org/.