if (document.images) {
  fs2node = new Image(); fs2node.src = "/i/freespace/fs2_nodemap.gif";
  revnode = new Image(); revnode.src = "/i/freespace/rev_nodemap.gif";
}

function imgTog(state) {
  if (document.images) {
    if (state) document.nodemap.src = fs2node.src;
    else document.nodemap.src = revnode.src;
  }
}