ns4 = (document.layers)? true:false
ie4 = (document.all)? true:false
ns6 = (document.getElementById)&&!document.all? true:false
op  = navigator.userAgent.toLowerCase().indexOf("opera")>=0;

function showLayer(prefix, nb, maxnb) {

	for (i=1;i<=maxnb;i++) {
		id = prefix+i;
		if (ie4) {
			obj = document.all[id]
		} else if (ns6) {
			obj = document.getElementById(id)
		}
		if (i==nb) 
			obj.style.visibility = "visible"
		else
			obj.style.visibility = "hidden"
	}
}