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

It can be applied between two constrained lines.

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

Public Class ParallelConstraint
Inherits GeometricalConstraint

public class ParallelConstraint : GeometricalConstraint;