anchor.diff:  ==== Fixed file trailer format differences between versions 1 and 2
   
   The following table shows common and different fields between fixed file trailers in versions 1 and 2.
  -Note that the size of the trailer is different depending on the version, so it is ``fixed'' only within one version.
  +Note that the size of the trailer is different depending on the version, so it is ''fixed'' only within one version.
   However, the version is always stored as the last four-byte integer in the file.
   
   .Differences between HFile Versions 1 and 2
  
positive.code: 
  . Data index -- version 2 multi-level block index, consisting of:
  .. Version 2 root index, stored in the data block index section of the file
  .. Optionally, version 2 intermediate levels, stored in the non%root format in   the data index section of the file. Intermediate levels can only be present if leaf level blocks are present
  .. Optionally, version 2 leaf levels, stored in the non%root format inline with   data blocks
  . Meta index -- version 2 root index format only, stored in the meta index section of the file
  . Bloom index -- version 2 root index format only, stored in the ``load-on-open'' section as part of Bloom filter metadata.
  
  ==== Root block index format in version 2
  
  
negative.code: For a multi-level block index we also store the following fields in the root index block in the load-on-open section of the HFile, in addition to the data structure described above:
  
  . Middle leaf index block offset
  . Middle leaf block on-disk size (meaning the leaf index block containing the reference to the ''middle'' data block of the file)
  . The index of the mid-key (defined below) in the middle leaf-level block.
  
  
  