[fitsbits] Inheritence diagram for FITS HDUs

[Paul Barrett]

Does anyone know of or have an inheritence diagram for FITS HDUs?  For example, 
the following is a first cut at such a diagram, but neglects the fact that a 
conforming extension can contain either image and record (binary table) data.


BaseHDU                    ExtensionHDU          CorruptedHDU
    |                            |
    |                  --------------------
PrimaryHDU           |                    |
    |          ConformingExtHDU     NonConformingHDU
    |                 |
GroupsHDU            |
                StandardExtHDU
                      |
          --------------------------
         |            |             |
    ImageExtHDU  TableExtHDU  BinTableExtHDU


For those of us who do object-oriented programming, this would be a big help.

  -- Paul