This class represents each object type that needs to be customized for quick properties.

Autodesk.AutoCAD.Customization.ElementBase
    Autodesk.AutoCAD.Customization.VersionableElement
        Autodesk.AutoCAD.Customization.CustomizationElement
        Autodesk.AutoCAD.Customization.ICustomizationContainer
            Autodesk.AutoCAD.Customization.ObjectType

Public Class ObjectType
Inherits CustomizationElement
Inherits INotifyPropertyChanged
Inherits ICustomizationContainer

public class ObjectType : CustomizationElement, INotifyPropertyChanged, ICustomizationContainer;