// -----------------------------------------------------------------------------
//   changing of layers for navigation subnav
// -----------------------------------------------------------------------------
if (document.layers) {
        visible = 'show';
        hidden = 'hide';

} else if (document.all) {
        visible = 'visible';
        hidden = 'hidden';
}

var lastItem = 'intro';

function changeLayer(item,navitem){

	if (document.layers) {
		daLast = document.layers[lastItem];
		daItem = document.layers[item];
        
	} else if (document.all) {
		daLast = document.all(lastItem).style;
		daItem = document.all(item).style;
	}

	daLast.visibility = hidden;
	daItem.visibility = visible;
	lastItem = item;
}