when you submit files with a form like this:

<form method="post" enctype="multipart/form-data">
	<input type="file" name="File[one][two][]"><br>
	<input type="file" name="File[one][two][]"><br>
	<input type="submit" value="go">
</form>

the superglobal $_FILES looks like this:

Array
(
  [File] => Array
    (
      [name] => Array
        (
          [one] => Array
            (
              [two] => Array
                (
                  [0] => empty.gif
                  [1] => header.gif
                )
            )
        )
      [type] => Array
        (
          [one] => Array
            (
              [two] => Array
                (
                  [0] => image/gif
                  [1] => image/gif
                )
            )
        )
      [tmp_name] => Array
        (
          [one] => Array
            (
              [two] => Array
                (
                  [0] => /tmp/phpuploads/php2ocF9K
                  [1] => /tmp/phpuploads/phpmUbo1l
                )
            )
        )
      [error] => Array
        (
          [one] => Array
            (
              [two] => Array
                (
                  [0] => 0
                  [1] => 0
                )
            )
        )
      [size] => Array
        (
          [one] => Array
            (
              [two] => Array
                (
                  [0] => 43
                  [1] => 5128
                )
            )
        )
    )
)

Personally I think this is not very logical, I would prefer something like this:

Array
(
  [File] => Array
    (
      [one] => Array
        (
          [two] => Array
            (
              [0] => Array
                (
                  [name] => empty.gif
                  [type] => image/gif
                  [tmp_name] => /tmp/phpuploads/php2ocF9K
                  [error] => 0
                  [size] => 43
                )
              [1] => Array
                (
                  [name] => header.gif
                  [type] => image/gif
                  [tmp_name] => /tmp/phpuploads/phpmUbo1l
                  [error] => 0
                  [size] => 5128
                )                
            )            
        )        
    )
)