if (document.images)
{
 navi_b1_off = new Image(); navi_b1_off.src = "grafa/adr1.gif"
 navi_b1_over = new Image(); navi_b1_over.src = "grafa/adr2.gif"
}

function turn_off(ImageName)
{
 if (document.images != null)
 {
  document[ImageName].src = eval(ImageName + "_off.src");
 }
}

function turn_over(ImageName)
{
 if (document.images != null)
 {
  document[ImageName].src = eval(ImageName + "_over.src");
 }
}