function exp_coll(ind)
{
 s = document.getElementById("sp_" + ind);
 if (s.style.display == 'none')
 {
   s.style.display = 'block';
 }
 else if (s.style.display == 'block')
 {
   s.style.display = 'none';
 }
}



/*
function coll_all()
{
  for (ind=1; ind <= 20; ind++) {
    x = document.getElementById("sp_" + ind);
    x.style.display = 'none';
    
    
  }
}

function exp_all()
{
  for (ind=1; ind <= 20; ind++) {
    x = document.getElementById("sp_" + ind);
    x.style.display = 'block';
   
  }
}
*/