function toggleLayer( whichLayer ){  var elem, vis;  if( document.getElementById )
// this is the way the standards work
elem = document.getElementById( whichLayer );  else if( document.all )
// this is the way old msie versions work
elem = document.all[whichLayer];  else if( document.layers )
// this is the way nn4 works
elem = document.layers[whichLayer];  vis = elem.style;
// if the style.display value is blank we try to figure it out here
if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)
vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';  vis.display = (vis.display==''||vis.display=='block')?'none':'block';}