That page uses javascript to submit the form on the onchecnge event of the select list:
for example:
html:
<form id="form1" name="form1" method="post" action="">
<label>
<select name="select" id="select" onChange="document.form1.submit()">
<option value="1">one</option>
<option value="2">two</option>
<option value="3">three</option>
</select>
</label>
</form>
In this case, you would so much be using dynamic drop downs. Since the form is posting each time the select list is changed, you can filter the recordset that populates the child list on the information submitted by the parent list. These two lists can also be used to filter the results recordset.
