This wraps the ObjectARX AcDbAssocSurfaceActionBody class.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.AssocActionBody
        Autodesk.AutoCAD.DatabaseServices.AssocParamBasedActionBody
            Autodesk.AutoCAD.DatabaseServices.AssocSurfaceActionBody
                Autodesk.AutoCAD.DatabaseServices.AssocEdgeFilletActionBody
                Autodesk.AutoCAD.DatabaseServices.AssocFilletSurfaceActionBody
                Autodesk.AutoCAD.DatabaseServices.AssocOffsetSurfaceActionBody
                Autodesk.AutoCAD.DatabaseServices.AssocPathBasedSurfaceActionBody

Public Class AssocSurfaceActionBody
Inherits AssocParamBasedActionBody

public class AssocSurfaceActionBody : AssocParamBasedActionBody;