for (var i in document)
{
  if (i=="images") swap =1;
}

p_im = new Array()
a_im = new Array()

if (swap)
 {
  for(var i=1;i<=4;i++) {
  p_men = new Image()
  p_men.src = "pix/menu_p.gif"
  a_men = new Image()
  a_men.src = "pix/menu_pa.gif"
  }
 }

function ion(targ) {
  if (document.images) eval('document.'+targ+'.src = a_men.src')
}

function ioff(targ) {
  if (document.images) eval('document.'+targ+'.src = p_men.src')
}