function swap(num,over){var imgid="img"+num;var imgsrc;if(over)
imgsrc="img/navigr"+num+".gif";else
imgsrc="img/navig"+num+".gif";var img=document.getElementById(imgid);img.src=imgsrc;}
function swapon(num){swap(num,true);}
function swapoff(num){swap(num,false);}