function na_show_layer(lname)
{
  if (na_show_layer.arguments.length <= 1) { // don't delete, backword compatibility
    if(document.getElementById) {
      document.getElementById(lname).style.visibility = 'visible';
    } else if(document.layers) {
      document.layers[lname].visibility = 'show'   
    } else if(document.all)
      document.all(lname).style.visibility = 'visible' 
  } else {
    if(document.getElementById) {
      document.getElementById(lname).style.visibility = 'hidden';
    } else if(document.layers) {
      document.layers[lname].visibility = 'hide'   
    } else if(document.all)
      document.all(lname).style.visibility = 'hidden' 
  }
}