Description:
------------
While understand that much of the SPL extension is undocumented, it occurs to me that there's a simple piece of documentation that could be added. 
On this page: http://us.php.net/manual/en/recursivedirectoryiterator.construct.php 
it refers to "flags" without telling what options there are for flags. Now it is documented here that there are flags defined as recursive iterator class constants http://us.php.net/manual/en/spl.constants.php , but I guessed that was unlikely to be all the flags possible. Thus I used the ReflectionClass to get all of RecursiveDirectoryIterator's class constants and got this array:

array(11) {
  ["CURRENT_MODE_MASK"]=>
  int(240)
  ["CURRENT_AS_PATHNAME"]=>
  int(32)
  ["CURRENT_AS_FILEINFO"]=>
  int(0)
  ["CURRENT_AS_SELF"]=>
  int(16)
  ["KEY_MODE_MASK"]=>
  int(3840)
  ["KEY_AS_PATHNAME"]=>
  int(0)
  ["FOLLOW_SYMLINKS"]=>
  int(512)
  ["KEY_AS_FILENAME"]=>
  int(256)
  ["NEW_CURRENT_AND_KEY"]=>
  int(256)
  ["SKIP_DOTS"]=>
  int(4096)
  ["UNIX_PATHS"]=>
  int(8192)
}


Test script:
---------------
$reflector = new ReflectionClass('RecursiveDirectoryIterator');
var_dump($reflector->getConstants());

Expected result:
----------------
array(11) {
  ["CURRENT_MODE_MASK"]=>
  int(240)
  ["CURRENT_AS_PATHNAME"]=>
  int(32)
  ["CURRENT_AS_FILEINFO"]=>
  int(0)
  ["CURRENT_AS_SELF"]=>
  int(16)
  ["KEY_MODE_MASK"]=>
  int(3840)
  ["KEY_AS_PATHNAME"]=>
  int(0)
  ["FOLLOW_SYMLINKS"]=>
  int(512)
  ["KEY_AS_FILENAME"]=>
  int(256)
  ["NEW_CURRENT_AND_KEY"]=>
  int(256)
  ["SKIP_DOTS"]=>
  int(4096)
  ["UNIX_PATHS"]=>
  int(8192)
}


Actual result:
--------------
array(11) {
  ["CURRENT_MODE_MASK"]=>
  int(240)
  ["CURRENT_AS_PATHNAME"]=>
  int(32)
  ["CURRENT_AS_FILEINFO"]=>
  int(0)
  ["CURRENT_AS_SELF"]=>
  int(16)
  ["KEY_MODE_MASK"]=>
  int(3840)
  ["KEY_AS_PATHNAME"]=>
  int(0)
  ["FOLLOW_SYMLINKS"]=>
  int(512)
  ["KEY_AS_FILENAME"]=>
  int(256)
  ["NEW_CURRENT_AND_KEY"]=>
  int(256)
  ["SKIP_DOTS"]=>
  int(4096)
  ["UNIX_PATHS"]=>
  int(8192)
}