This .NET class wraps the AcGePointEnt3d ObjectARX class. It's an abstract base class for 3D point classes.

Autodesk.AutoCAD.Geometry.Entity3d
    Autodesk.AutoCAD.Geometry.PointEntity3d
        Autodesk.AutoCAD.Geometry.PointOnCurve3d
        Autodesk.AutoCAD.Geometry.PointOnSurface
        Autodesk.AutoCAD.Geometry.Position3d

Public abstract Class PointEntity3d
Inherits Entity3d

public abstract class PointEntity3d : Entity3d;