function gramajes_carpeteria(){
switch (document.form1.papel_port.value){
 case 'Estucado brillo':
 case 'Estucado mate':
 case 'No estucado':
  var gramajes=new Array("300","250");
  break;
 case 'Verjurado':
  var gramajes=new Array("250");	
  break;
 case 'Cartulina':
  var gramajes=new Array("250","180");	
  break;
 case 'Otro:':
  var gramajes=new Array("Otro:");
	break;
 }
if (document.form1.papel_port.value=='Otro:'){
 document.getElementById('span_papel_port').style.visibility='visible';
 document.getElementById('span_gramaje_port').style.visibility='visible';
 }else{
   document.getElementById('span_papel_port').style.visibility='hidden';
	 document.getElementById('span_gramaje_port').style.visibility='hidden';
	 }
document.form1.gramaje_port.length = gramajes.length;
for(i=0; i<gramajes.length; i++){ 
 document.form1.gramaje_port.options[i].id=gramajes[i]+'port';
 document.form1.gramaje_port.options[i].value=gramajes[i];
 document.form1.gramaje_port.options[i].text=gramajes[i]; 
 } 
if(document.form1.papel_port.value.indexOf('stucado')!=-1)
 document.getElementById('300port').selected=true;
if(document.form1.papel_port.value=='Cartulina')
 document.getElementById('250port').selected=true;
}