<select style='width:200px;'  id="combo_zone1" name="alfa1">
        <option value="1">a00</option>
        <option value="2">a01</option>
        <option value="3" selected>a02</option>
        <option value="4">a10</option>
        <option value="5">a11</option>
        <option value="6">a12</option>
        <option value="7">b00</option>
        <option value="8">b01</option>
        <option value="9">b02</option>
        <option value="10">b10</option>
        <option value="11">b11</option>
        <option value="12">b12</option>
        <option value="13">a22</option>
        <option value="14">a31</option>
        <option value="15">a04</option>
    </select>
    <script>
 
        var z=dhtmlXComboFromSelect("combo_zone1");</script>

 
    <div id="combo_zone2" style="width:200px; height:30px;"></div>
    <script>
 
        var z=new dhtmlXCombo("combo_zone2","alfa2",200);
        z.loadXML("data.xml");</script>

 
    <div id="combo_zone3" style="width:200px; height:30px;"></div>
    <script>
 
        var z=new dhtmlXCombo("combo_zone3","alfa3",200);
        z.addOption([[1,1111],[2,2222],[3,3333],[4,4444],[5,5555]]);</script>