if (document.images) {            
	sn = new Image();
	sa = new Image();
}

function HoverAOn(imgName) {document['mnu_'+imgName].src='imag/mnu_'+imgName+'_off.gif';}
function HoverAOff(imgName) {document['mnu_'+imgName].src='imag/mnu_'+imgName+'_on.gif'}