This .NET class wraps the AcDbUnderlayFile ObjectARX class. 

This interface is implemented by host applications that wish to support underlays. UnderlayDefinition and AcDbUnderlayReference objects use this interface to accomplish their mission.

Autodesk.AutoCAD.DatabaseServices.UnderlayFile

Public sealed Class UnderlayFile
Inherits DisposableWrapper

public sealed class UnderlayFile : DisposableWrapper;