if (document.images) {
  choice1=new Image();choice2=new Image();
  choice1.src="bullet.gif"; choice2.src="placeholder.gif";
}
function display(num) {
  if (document.images) {
    if (num=="1") document.link1.src=choice1.src;if (num=="2") document.link1.src=choice2.src;
    if (num=="3") document.link2.src=choice1.src;if (num=="4") document.link2.src=choice2.src;
    if (num=="5") document.link3.src=choice1.src;if (num=="6") document.link3.src=choice2.src;
    if (num=="7") document.link4.src=choice1.src;if (num=="8") document.link4.src=choice2.src;
    if (num=="9") document.link5.src=choice1.src;if (num=="10") document.link5.src=choice2.src;
    if (num=="11") document.link6.src=choice1.src;if (num=="12") document.link6.src=choice2.src;
  }
}