anchor.diff:          {ok, Fd} ->
               case file:read(Fd, 2) of
                   %% Verify magic number is intact
  -                {ok, <<16#b00c:16/integer>>} ->
  +                {ok, ?MAGIC_NUMBER} ->
                       %% Skip past checksum data for now
                       {ok, ?TOTAL_HEADER_SIZE_BYTES} = file:position(Fd, {bof, ?TOTAL_HEADER_SIZE_BYTES}),
                       {ok, #entryref{fd=Fd, path=FileName}};
  
positive.code:     case file:open(FileName, [exclusive, write, binary]) of
          {ok, Fd} ->
              %% Magic number to guard against file corruption
              case file:write(Fd, <<16#b00c:16/integer>>) of
                  ok ->
                      {ok, ?TOTAL_HEADER_SIZE_BYTES} = file:position(Fd, {bof, ?TOTAL_HEADER_SIZE_BYTES}),
                      {ok, #entryref{fd=Fd, path=FileName, ctx=erlang:md5_init()}};
  
negative.code: -include_lib("kernel/include/file.hrl").
  -include("bksw_obj.hrl").
  
  -define(MAGIC_NUMBER, <<16#b00c:16/integer>>).
  -define(MAGIC_NUMBER_SIZE_BYTES, 2).
  -define(CHECKSUM_SIZE_BYTES, 16).
  -define(TOTAL_HEADER_SIZE_BYTES, ?MAGIC_NUMBER_SIZE_BYTES + ?CHECKSUM_SIZE_BYTES).
  