| interface  | IExtensions | A model object that contains the portion of the plug-in model
 responsible for extensions and extension points. | 
| interface  | IFragment | A model object that represents the content of the fragment.xml
 file. | 
| interface  | IPlugin | A model object that represents the content of the plugin.xml
 file. | 
| interface  | IPluginAttribute | An attribute of XML elements found in the plug-in. | 
| interface  | IPluginBase | A model object that represents the content of a plug-in or
 fragment manifest. | 
| interface  | IPluginElement | Classes that implement this interface model the
 XML elements found in the plug-in model. | 
| interface  | IPluginExtension | Classes that implement this interface model the extension
 element found in the plug-in or fragment manifest. | 
| interface  | IPluginExtensionPoint | Classes that implement this interface model an extension point
 element specified in the plug-in manifest. | 
| interface  | IPluginImport | Objects that implement this interface represent references
 to required plug-ins. | 
| interface  | IPluginLibrary | The class that implements this interface represents a
 reference to the library that is defined in the plug-in
 manifest. | 
| interface  | IPluginObject | A base interface for all the objects in the plug-in model. | 
| interface  | IPluginParent | Classes that implement this interface are
 capable of containing other plug-in objects. |