This is class Autodesk.AutoCAD.DatabaseServices.AssocBlendSurfaceActionBody.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.AssocActionBody
        Autodesk.AutoCAD.DatabaseServices.AssocParamBasedActionBody
            Autodesk.AutoCAD.DatabaseServices.AssocSurfaceActionBody
                Autodesk.AutoCAD.DatabaseServices.AssocPathBasedSurfaceActionBody
                    Autodesk.AutoCAD.DatabaseServices.AssocBlendSurfaceActionBody

Public Class AssocBlendSurfaceActionBody
Inherits AssocPathBasedSurfaceActionBody

public class AssocBlendSurfaceActionBody : AssocPathBasedSurfaceActionBody;