This class represents a Vertical constraint node in the owning Assoc2dConstraintGroup. 

It can be applied on one constrained line.

Autodesk.AutoCAD.DatabaseServices.ConstraintGroupNode
    Autodesk.AutoCAD.DatabaseServices.GeometricalConstraint
        Autodesk.AutoCAD.DatabaseServices.ParallelConstraint
            Autodesk.AutoCAD.DatabaseServices.VerticalConstraint

Public Class VerticalConstraint
Inherits ParallelConstraint

public class VerticalConstraint : ParallelConstraint;