function changeTabNav(n) {
	var tn1 = document.getElementById("tabNav1");
	var tn2 = document.getElementById("tabNav2");
	var tn3 = document.getElementById("tabNav3");
	var tnt1 = document.getElementById("tabNavTable1");
	var tnt2 = document.getElementById("tabNavTable2");
	var tnt3 = document.getElementById("tabNavTable3");
	
	if (tn1 && tnt1) {
		tn1.className = (n==1 ? "navTabOn" : "navTabOff");
		tnt1.style.display = (n==1 ? "" : "none");
	}
	if (tn2 && tnt2) {
		tn2.className = (n==2 ? "navTabOn" : "navTabOff");
		tnt2.style.display = (n==2 ? "" : "none");
	}
	if (tn3 && tnt3) {
		tn3.className = (n==3 ? "navTabOn" : "navTabOff");
		tnt3.style.display = (n==3 ? "" : "none");
	}
}