$_POST : Proč mizí hranaté závorky?

<form action='test.php' method='post' enctype='multipart/form-data'>
<input type='checkbox' name='Access[Kurz[EUR]]' value='1' checked >
<input type='checkbox' name='Access[Kurz[x][y]]' value='1' checked >
<input type='submit' name='Save' value='Save'>
</form>
<?php
echo "<xmp>";
var_dump($_POST);
echo "</xmp>";

----
// Po odeslání:

array(2) {
  ["Access"]=>
  array(2) {
    ["Kurz[EUR"]=>
    string(1) "1"
    ["Kurz[x"]=>
    array(1) {
      ["y"]=>
      string(1) "1"
    }
  }
  ["Save"]=>
  string(4) "Save"
}