function checkLayer(theName) {
 for (i=0;i<groupLayers.length;i++) {
      if (theName == groupLayers[i]) {
	  return true;
	  break
	  }
 }
  return false;
}

function setGroup(theVal) {
 var theName;
  if (theVal == 1) { groupVisible = true
   } else { groupVisible = false }
 for(var ii=0;ii<layerCount;ii++) {
     theName = LayerName[ii];
	  if (checkLayer(theName) == true) {
	   LayerVisible[ii] = theVal;     
 	  }
 }
}