This class represents an angle constraint node in the owning Assoc2dConstraintGroup. 

It can be applied between 3 constrained points.

Autodesk.AutoCAD.DatabaseServices.ConstraintGroupNode
    Autodesk.AutoCAD.DatabaseServices.GeometricalConstraint
        Autodesk.AutoCAD.DatabaseServices.ExplicitConstraint
            Autodesk.AutoCAD.DatabaseServices.AngularConstraint
                Autodesk.AutoCAD.DatabaseServices.ThreePointAngleConstraint

Public Class ThreePointAngleConstraint
Inherits AngularConstraint

public class ThreePointAngleConstraint : AngularConstraint;