This .NET class wraps the AcGeLineSeg3d ObjectARX class. It represents a bounded line segment in 3D space.

Autodesk.AutoCAD.Geometry.Entity3d
    Autodesk.AutoCAD.Geometry.Curve3d
        Autodesk.AutoCAD.Geometry.LinearEntity3d
            Autodesk.AutoCAD.Geometry.LineSegment3d

Public sealed Class LineSegment3d
Inherits LinearEntity3d

public sealed class LineSegment3d : LinearEntity3d;