if(document.images)
{
  tm_B1_off = new Image(); tm_B1_off.src = "/buttons/tm_B1.gif"
  tm_B1_over = new Image(); tm_B1_over.src = "/buttons/tm_B1_on.gif"
  tm_B2_off = new Image(); tm_B2_off.src = "/buttons/tm_B2.gif"
  tm_B2_over = new Image(); tm_B2_over.src = "/buttons/tm_B2_on.gif"
  tm_B3_off = new Image(); tm_B3_off.src = "/buttons/tm_B3.gif"
  tm_B3_over = new Image(); tm_B3_over.src = "/buttons/tm_B3_on.gif"
  tm_B4_off = new Image(); tm_B4_off.src = "/buttons/tm_B4.gif"
  tm_B4_over = new Image(); tm_B4_over.src = "/buttons/tm_B4_on.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");
    }
}