Código:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3c.org/TR/1999/REC-html401-19991224/loose.dtd">
<html>
<head>
</head>
<body>
<form name="select" method="post">
<select name="documento1" id="or1" 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:visible"> </select>
<script type="text/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="or2" 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="documento11"></label>
<select name="documento22" id="documento22" style="visibility:visible"> </select>
<script type="text/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="or3" onchange="Combos3(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="documento33" id="documento33" style="visibility:visible"> </select>
<script type="text/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>
</body>
</html>
¿Y por qué no usas un solo escript para los tres, preferentemente en el
head ?