}
   if (document.all) {
      //IE4+ specific code
      pre = 'document.all.';
      post = '.style'; }

function layer_exists(layer) {
   try {
      eval(pre + layer + post);
      return true; }
   catch (error) {
      return false; }}

function show_layer(layer) {
   eval(pre + layer + post).position = 'relative'; 
   eval(pre + layer + post).visibility = 'visible'; }

function hide_layer(layer) {
   eval(pre + layer + post).visibility = 'hidden';
   eval(pre + layer + post).positi