function clean(obj, type){
   if(obj.className == 0){
     obj.className = 1;
     obj.value = '';
     if(type == 2){
       obj.type = "password";
     }
   }
 }
 
 function resetField(obj,type){
   if(obj.className == 1){
     if(obj.value.length == 0){
       obj.className = 0;
       if(type == 1){
         obj.value = "usuario";
       } else {
         obj.type = "text";
         obj.value = "password";
       }
     }
   }
 }