var state = 'none';
function showhide(layer_ref) {
 if (state == 'block') {
  state = 'none';
 } else {
  state = 'block';
 }
 if (document.all) {
  eval( "document.all." + layer_ref + ".style.display = state");
 }
 if (document.getElementById &&!document.all) {
  hza = document.getElementById(layer_ref);
  hza.style.display = state;
 }
}