IfcProject represents processes in design, engineering, construction, or maintenance activities performed for a product. The project forms the context for exchangeable information and it may optionally represent a construction project. The main aim of IfcProject's in an exchange structure is to provide the root instance and the context for other information items. 

The context related to the project:

• the default units
• the geometric representation context with shape representations
  • coordinate system of the project
  • the coordinate space dimension
  • the precision used for the geometric representations
  • [optional] the indication of the True North
  • [optional] conversion utilities between the project coordinate system and the geospatial coordinate reference system.

changes 

• IFC4 changes: The attributes RepresentationContexts and UnitsInContext are made optional and are promoted to supertype IfcContext.