// -------------------------------------------------------------------------
function hide_or_show_select (en, sel) {
   sel.disabled = !en.checked;
}
// -------------------------------------------------------------------------
function interlock (src, dst) {
   dst.disabled = src.checked;
   if (dst.disabled) {
      dst.checked = 0;
      if (dst.onchange)
         dst.onchange();
   }
}
// -------------------------------------------------------------------------