This .NET class wraps the AcGePlane ObjectARX class. Plane represents a parameterized infinite plane in 3D space.

Autodesk.AutoCAD.Geometry.Entity3d
    Autodesk.AutoCAD.Geometry.Surface
        Autodesk.AutoCAD.Geometry.PlanarEntity
            Autodesk.AutoCAD.Geometry.Plane

Public sealed Class Plane
Inherits PlanarEntity

public sealed class Plane : PlanarEntity;