How to use WWWForm to post multi-valued data?

You know how you can have radio buttons or checkboxes or other multi-select fields on an HTML form? I need to translate that into a WWW request from within my app, figuring WWWForm would be the thing to use. Simple enough with simple single-value fields. What's the syntax for constructing a multi-value field?

In other words, if the HTML were like this:

<form action="buy_snacks.php" method="post">
<select multiple name="snacks[ ]">
  <option value="coke">CocaCola</option>
  <option value="popcorn">Popcorn</option>
  <option value="peanuts">Peanuts</option>
</select>
</form>

and the PHP were like this:

<?php
$snacks = $_POST['snacks'];
// Note that $snacks will be an array.
foreach ($snacks as $s) {
  echo "$s
";
}
?>

What's the missing intermediate step here, the actual format of the data, that I'd use with the WWWForm object. Essentially, how do I convert that HTML to a Unity script, indicating my selections? (Or is there a better way?)

Why yes, quite simple, eg:

  form.AddField ("snacks[]", "peanuts");
  form.AddField ("snacks[]", "popcorn");