public const string ifcenginedll = @"ifcengine.dll";

[DllImport(IFCEngineDLL, EntryPoint = "getRootAxis2Placement")]
public static extern Int64 getRootAxis2Placement(Int64 model, byte exclusiveIfHasGeometry);    

Property model

Size: 64 bit / 8 byte (value)
The handle to the model. The model handle is static during its existance. Several models can be opened simultaniously within one session. Different models are always independent, threads are allowed to be running on different models simultaniously.

Property exclusiveIfHasGeometry

Size: 8 bit / 1 byte (value)