var NUM_OPCIONS=2;
var NUM_SUBOPCIONS=5;
function subOpcions(num){     
    if(num!=2){
     for(i=1;i<=NUM_SUBOPCIONS;i++){
      obj=document.getElementById("subOpcio2_"+i);
      obj2=document.getElementById("tdopcio"+i);
      obj.style.visibility='hidden';
      obj.style.display='none';
     }
    }
    for(i=1;i<=NUM_OPCIONS;i++){
      obj=document.getElementById("subOpcio"+i);
        obj2=document.getElementById("tdopcio"+i);
      if(i==num){
        obj.style.visibility='visible';
        obj.style.display='block';
        if(obj2) obj2.style.backgroundColor="#FFFFFF";
      }
      else{
        obj.style.visibility='hidden';
        obj.style.display='none';
         if(obj2) obj2.style.backgroundColor="";
      }
    }
 }
function subsubOpcio(sopcio,num){ 
    for(i=1;i<=NUM_SUBOPCIONS;i++){
      obj=document.getElementById("subOpcio"+sopcio+"_"+i);
       obj2=document.getElementById("tdsubopcio"+sopcio+"_"+i);
      if(i==num){
        obj.style.visibility='visible';
        obj.style.display='block';
        if(obj2) obj2.style.backgroundColor="#FFFFFF";         
      }
      else{
        obj.style.visibility='hidden';
        obj.style.display='none';
         if(obj2) obj2.style.backgroundColor="";      
      }
    }
}    

function subOpcionsoff(num){     
    for(i=1;i<=NUM_OPCIONS;i++){
      obj=document.getElementById("subOpcio"+i);
      if(i==num){
        obj.style.visibility='hidden';
        obj.style.display='none';
      }
    }
    if(num!=2){
     for(i=1;i<=NUM_SUBOPCIONS;i++){
      obj=document.getElementById("subOpcio2_"+i);
      obj.style.visibility='hidden';
      obj.style.display='none';
     }
    }    
}
<!--
function MM_reloadPage(init) {  //reloads the window if Nav4 resized
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    document.MM_pgW=innerWidth; document.MM_pgH=innerHeight; onresize=MM_reloadPage; }}
  else if (innerWidth!=document.MM_pgW || innerHeight!=document.MM_pgH) location.reload();
}
MM_reloadPage(true);
//-->
usuario="secretaria"
dominio="biada.com" 
conector="@"

function dame_correo(){
   return usuario + conector + dominio
}

function escribe_enlace_correo(){
   document.write("<a class=\"adress\" href='mailto:" + dame_correo() + "'>" + dame_correo() + "</a>")
}