(PHP 4 >= 4.0.2, PHP 5)
mcrypt_module_is_block_algorithm_mode — Returns if the specified module is a block algorithm or not
$mode
   [, string $lib_dir
  ] )
   This function returns TRUE if the mode is for use with block
   algorithms, otherwise it returns FALSE. (e.g. FALSE for stream, and
   TRUE for cbc, cfb, ofb).
  
modeThe mode to check.
lib_dir
       The optional lib_dir parameter can contain the
       location where the algorithm module is on the system.
      
   This function returns TRUE if the mode is for use with block
   algorithms, otherwise it returns FALSE. (e.g. FALSE for stream, and
   TRUE for cbc, cfb, ofb).