Bad Block Descriptor Layout


               |-------------------|-------------------|
               |  LBN Field Size   | Count Field Size  |
               |-------------------|-------------------|
               | Map Words Avail.  | Map Words in Use  |
               |-------------------|-------------------|
               |                                       |
               |                                       |
               |                                       |
               |          Retrieval Pointers           |
               |                                       |
               |                                       |
               |                                       |
               |---------------------------------------|
               |            Block Checksum             |
               |---------------------------------------|