This .NET class wraps the AcGeBoundBlock2d ObjectARX class. 

This class provides a two-dimensional bounding volume implementation. 

Bounding blocks may exist in two forms: as an ordinary coordinate-aligned bounding box and as a parallelogram.

Autodesk.AutoCAD.Geometry.Entity2d
    Autodesk.AutoCAD.Geometry.BoundBlock2d

Public sealed Class BoundBlock2d
Inherits Entity2d

public sealed class BoundBlock2d : Entity2d;