anchor.diff:      {ok, Result, NewHeight, _HeightDiff} = seedtree_write(
               Fd, Seedtree3, TargetTreeHeight - Seedtree3#seedtree_root.height),
   
  -    % NOTE vmx: I assume that the height can't change more than 1 level
  -    %     at a time, not really sure though
  -    % XXX vmx (2010-12-09): now we know the heihgt difference
       {NewPos, NewHeight2, NewMbr} = case length(Result) of
       % single node as root
       1 ->
  
positive.code:         end;
      % insert new tree into target tree
      Diff when Diff > 0 ->
      %?debugMsg("target tree higher"),
          {ok, _, SubPos, Inc} = insert_subtree(Fd, TargetPos, MbrAndPosList, Diff-1),
          {SubPos, TargetHeight+Inc};
      % insert target tree into new tree
      Diff when Diff < 0 ->
      %?debugMsg("target tree smaller"),
          % NOTE vmx: I don't think this case can ever happen
          %case length(MbrAndPosList) of
          %1 ->
  
negative.code:     % Both, the new bulk loaded tree and targt tree have the same height
      % => create new common root
      Diff when Diff == 0 ->
      ?debugMsg("same height"),
          if
          length(MbrAndPosList) + 1 =< ?MAX_FILLED ->
              %Mbrs = [Mbr || {Mbr, Pos} <- MbrAndPosList],
  