This .NET class wraps the AcDbSequenceEnd ObjectARX class. 

The SequenceEnd class represents the SEQEND entity within AutoCAD. Objects of this class are created and handled automatically by AutoCAD for each complex entity that requires them, such as BlockReference, AcDb2dPolyline, 3dPolyline, etc. 

Applications do not need to create objects of this class, nor do they need to add or remove them from databases. Applications are free to add or manipulate xdata on objects of this class, as well as work with extension dictionaries for objects of this class.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.Entity
        Autodesk.AutoCAD.DatabaseServices.SequenceEnd

Public sealed Class SequenceEnd
Inherits Entity

public sealed class SequenceEnd : Entity;

Do not derive from this class. Attempting to do so will cause your application to halt AutoCAD.