function toggleLayer(whichLayer)
{
 if (document.getElementById)
 {
 // this is the way the standards work
 var style2 = document.getElementById(whichLayer).style;
 style2.display = style2.display? "":"block";
 }
 else if (document.all)
 {
 // this is the way old msie versions work
 var style2 = document.all[whichLayer].style;
 style2.display = style2.display? "":"block";
 }
 else if (document.layers)
 {
 // this is the way nn4 works
 var style2 = document.layers[whichLayer].style;
 style2.display = style2.display? "":"block";
 }
}