Código:
<form name="select" method="post">
<select name="documento1" id="or" onchange="Combos1(this)">
<option value=" "></option>
<option value="No">No</option>
<option value="Si">Si</option>
<option value="N/A">N/A</option>
</select>
<label for="documento11"></label>
<select name="documento11" id="documento11" style="visibility:text"> </select>
<script language="javascript">
function Combos1(x) {
ItDepend=document.getElementById('documento11');
if(!ItDepend){return;}
var mitems=new Array();
mitems['Si']=['Si'];
mitems['No']=['No'];
mitems['N/A']=['N/A'];
ItDepend.options.length=0; ItActual=mitems[x.options[x.selectedIndex].value];
if(!ItActual){return;} ItDepend.options.length=ItActual.length;
for(var i=0;i<ItActual.length;i++) {
ItDepend.options[i].text=ItActual[i];
ItDepend.options[i].value=ItActual[i]; }}
</script>
<br>
<select name="documento2" id="or" onchange="Combos2(this)">
<option value=" "></option>
<option value="No">No</option>
<option value="Si">Si</option>
<option value="N/A">N/A</option>
</select>
<label for="documento22"></label>
<select name="documento22" id="documento2" style="visibility:text" > </select>
<script language="javascript">
function Combos2(x) {
ItDepend=document.getElementById('documento22');
if(!ItDepend){return;}
var mitems=new Array();
mitems['Si']=['Si'];
mitems['No']=['No'];
mitems['N/A']=['N/A'];
ItDepend.options.length=0; ItActual=mitems[x.options[x.selectedIndex].value];
if(!ItActual){return;} ItDepend.options.length=ItActual.length;
for(var i=0;i<ItActual.length;i++) {
ItDepend.options[i].text=ItActual[i];
ItDepend.options[i].value=ItActual[i]; }}
</script>
<br>
<select name="documento3" id="or" onchange="Combos3(this)">
<option value=" "></option>
<option value="No">No</option>
<option value="Si">Si</option>
<option value="N/A">N/A</option>
</select></td><td>
<label for="documento33"></label>
<select name="documento33" id="documento3" style="visibility:text" > </select>
<script language="javascript">
function Combos3(x) {
ItDepend=document.getElementById('documento33');
if(!ItDepend){return;}
var mitems=new Array();
mitems['Si']=['Si'];
mitems['No']=['No'];
mitems['N/A']=['N/A'];
ItDepend.options.length=0; ItActual=mitems[x.options[x.selectedIndex].value];
if(!ItActual){return;} ItDepend.options.length=ItActual.length;
for(var i=0;i<ItActual.length;i++) {
ItDepend.options[i].text=ItActual[i];
ItDepend.options[i].value=ItActual[i]; }}
</script>
</form>

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