-- DavidHeath - 18 Feb 2004

   A
   ^
   |    denotes that B is a specialisation of A
   B


                          GenericDataObject
                                 ^
                                 | 
                        TypedGenericDataObject
                                 ^
                                 |
                          PersistentBlock
                                 ^
                                 |
                                 +-------------------------------------+ 
                                 |                                     |
                                 |                               ContainerBlock
                                 |                                     ^
                                 |                   +-----------------+---------+----------------------+
                                 |                   |                           |                      |
                                 |        MultiColumnContainerBlock       CategoryContainerBlock     ContainerWithHeadingBlock
                                 |
                          BlockWithHeading
                                 ^
                                 |
                     +-----------+---------+---------------------------+---------------------+        
                     |                     |                           |                     |
                  ArticleBlock       PartnerFilterBlock          SingleArticleBlock      TextBlock
                     ^
                     | 
         +-----------+---------+--------------------+
         |                     |                    |
 ArticleFilterBlock    ArticleListBlock      ArticleCountryBlock