How can I set more variables in the array?

I use a function:
update: function () {
        list = $(this).nestedSortable('toArray', {startDepthCount: 0});
        $.post('ajax.php', { list: list }, function(data){ $("#result").hide().html(data).fadeIn('slow')}, "html");
    }
To send the variables to another page and save them on a database (I got this from: http://stackoverflow.com/questions/5240114/need-help-getting-the-output-from-nestedsortable-jquery)

When I do a var_dump on the data recived it displays the following:
array (size=1)
  'list' => 
    array (size=7)
      0 => 
        array (size=5)
          'item_id' => string '' (length=0)
          'parent_id' => string '' (length=0)
          'depth' => string '0' (length=1)
          'left' => string '1' (length=1)
          'right' => string '14' (length=2)
      1 => 
        array (size=5)
          'item_id' => string '2' (length=1)
          'parent_id' => string '' (length=0)
          'depth' => string '1' (length=1)
          'left' => string '2' (length=1)
          'right' => string '9' (length=1)
      2 => 

How can I also send another value like a table name that changes within each item_id?

THanks!!