if (document.images) {

left01_on = new Image();
left01_on.src = "images/btn_left_01_on.gif";
left01 = new Image();
left01.src = "images/btn_left_01.gif";

left02_on = new Image();
left02_on.src = "images/btn_left_02_on.gif";
left02 = new Image();
left02.src = "images/btn_left_02.gif";

left03_on = new Image();
left03_on.src = "images/btn_left_03_on.gif";
left03 = new Image();
left03.src = "images/btn_left_03.gif";

left04_on = new Image();
left04_on.src = "images/btn_left_04_on.gif";
left04 = new Image();
left04.src = "images/btn_left_04.gif";





right01_on = new Image();
right01_on.src = "images/btn_right_01_on.gif";
right01 = new Image();
right01.src = "images/btn_right_01.gif";

right02_on = new Image();
right02_on.src = "images/btn_right_02_on.gif";
right02 = new Image();
right02.src = "images/btn_right_02.gif";

right03_on = new Image();
right03_on.src = "images/btn_right_03_on.gif";
right03 = new Image();
right03.src = "images/btn_right_03.gif";

}


function imageOn(imageName){
  document[imageName].src = eval(imageName+"_on.src");
}

function imageOff(imageName){
  document[imageName].src = eval(imageName+".src");
}