This .NET class wraps the AcDbLayout ObjectARX class. 

An Layout object stores characteristics of each paperspace layout. Layout objects are stored in an Dictionary object with an ACAD_LAYOUT key, allowing easy iteration and indexing.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.PlotSettings
        Autodesk.AutoCAD.DatabaseServices.Layout

Public Class Layout
Inherits PlotSettings

public class Layout : PlotSettings;