if(document.images) {
 var imgs = new Array();
 imgs[0] = new Image();  imgs[0].src = "img/left_menu01A.gif";
 imgs[1] = new Image();  imgs[1].src = "img/left_menu01B.gif";
 imgs[2] = new Image();  imgs[2].src = "img/left_menu02A.gif";
 imgs[3] = new Image();  imgs[3].src = "img/left_menu02B.gif";
 imgs[4] = new Image();  imgs[4].src = "img/left_menu03A.gif";
 imgs[5] = new Image();  imgs[5].src = "img/left_menu03B.gif";
 imgs[6] = new Image();  imgs[6].src = "img/left_menu04A.gif";
 imgs[7] = new Image();  imgs[7].src = "img/left_menu04B.gif";
 imgs[8] = new Image();  imgs[8].src = "img/left_menu05A.gif";
 imgs[9] = new Image();  imgs[9].src = "img/left_menu05B.gif";
 imgs[10] = new Image();  imgs[10].src = "img/left_menu06A.gif";
 imgs[11] = new Image();  imgs[11].src = "img/left_menu06B.gif";
}

function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}