Here are additional third party resources to check out:
The international organization that emphasizes the demonstration of "... the efficiency and sustainability benefits that true interoperability can deliver and to help members and their supply chains in implementation." It is responsible for the development and management of IFC.
A council of the National Institute of Building Sciences (NIBS), coordinating the U.S. efforts of promoting interoperability in the real property industry.
The focal point for the activities in establishing standards regarding the use of BIM methodologies and technologies in the U.S.
The GSA is considered the largest landlord in the U.S. and has made extensive efforts in transforming their organization by integrating BIM methodologies and technologies into the design, construction administration, and facility management of U.S. federal properties.
The online technical reference documentation for IFC 2x3.
The online technical reference documentation for the use of Model View Definitions (MVDs), documenting the IFC data requirements for exchanges of BIM information between applications.