var layerDisplayStatus = new Array;
// switch layer visibility
function toggleLayerDisplay(whichLayer, status) {
	// store current layer status
	layerDisplayStatus[whichLayer] = status;
	// status: 'none', 'block'	
	if (document.getElementById) {
		// this is the way the standards work
		document.getElementById(whichLayer).style.display = status;
	}
	else if (document.all) {
		// this is the way old msie versions work
		document.all[whichLayer].style.display = status;
	}
	else if (document.layers) {
		// this is the way nn4 works
		document.layers[whichLayer].display = status;
	}
}