This .NET class wraps the AcGeLine2d ObjectARX class. It represents an unbounded line in 2D space.

Autodesk.AutoCAD.Geometry.Entity2d
    Autodesk.AutoCAD.Geometry.Curve2d
        Autodesk.AutoCAD.Geometry.LinearEntity2d
            Autodesk.AutoCAD.Geometry.Line2d

Public sealed Class Line2d
Inherits LinearEntity2d

public sealed class Line2d : LinearEntity2d;