This .NET class wraps the AcDbRay ObjectARX class. 

The Ray class represents the RAY entity type within AutoCAD. 

A ray entity is a line that has a start point, but continues on to infinity in some direction.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.Entity
        Autodesk.AutoCAD.DatabaseServices.Curve
            Autodesk.AutoCAD.DatabaseServices.Ray

Public Class Ray
Inherits Curve

public class Ray : Curve;

DBObject, Entity, Point3d, Vector3d