function showHideLayer(theLayer, theVisibility) {
	if (document.getElementById){
		var theStyle = document.getElementById(theLayer).style;
	}	else if (document.all) {
		var theStyle = document.all[theLayer].style;
	}	else if (document.layers)	{
		var theStyle = document.layers[theLayer].style;
	}
	theStyle.display = theVisibility ? "" : "none";
}