(PECL xdiff >= 0.2.0)
xdiff_string_merge3 — Merge 3 strings into one
$old_data
   , string $new_data1
   , string $new_data2
   [, string &$error
  ] )
   Merges three strings into one and returns the result.
   The old_data is an original version of data 
   while new_data1 and new_data2 are modified 
   versions of an original. An optional error is used to pass any
   rejected parts during merging process.
  
old_dataFirst string with data. It acts as "old" data.
new_data1
       Second string with data. It acts as modified version of old_data.
      
new_data2
       Third string with data. It acts as modified version of old_data.
      
errorIf provided then rejected parts are stored inside this variable.
   Returns the merged string, FALSE if an internal error happened, or TRUE
   if merged string is empty.