anchor.diff:  -spec find(table(), machi_dt:file_offset(), machi_dt:file_size()) ->
                     list({machi_dt:file_offset(),
                           machi_dt:file_size(),
  -                        machi_dt:chunk_csum()}).
  +                        machi_dt:chunk_csum()|trimmed}).
   find(#machi_csum_table{table=T}, Offset, Size) ->
       ets:select(T, [{{'$1', '$2', '$3'},
                       [inclusion_match_spec(Offset, Size)],
  
positive.code:     runthru(ets:tab2list(T), 0, Pos).
  
  -spec any_trimmed(table(),
                    machi_dt:chunk_pos(),
                    machi_dt:chunk_size()) -> boolean().
  any_trimmed(CsumT, Offset, Size) ->
      Chunks = find(CsumT, Offset, Size),
  
negative.code: 
  -spec open(string(), proplists:proplist()) ->
                    {ok, table()} | {error, file:posix()}.
  
  open(CSumFilename, _Opts) ->
      T = ets:new(?MODULE, [private, ordered_set]),
      CSum = machi_util:make_tagged_csum(none),
      %% Dummy entry for headers
      true = ets:insert_new(T, {0, ?MINIMUM_OFFSET, CSum}),
      C0 = #machi_csum_table{
              file=CSumFilename,
              table=T},
      case file:read_file(CSumFilename) of
          {ok, Bin} ->
              List = case split_checksum_list_blob_decode(Bin) of
                         {List0, <<>>} ->
  