function TOC(category, onOrOff) {
  var jpg = "";
  if (category == 'catalog') {
    if (onOrOff == 'on') {
      jpg = "/images/GB-TOCgreenCatalogOn.jpg";
    } else {
      jpg = "/images/GB-TOCgreenCatalogOff.jpg";
    }
   document.getElementById('TOCcatalog').src = jpg; 
  }  

  if (category == 'about') {
    if (onOrOff == 'on') {
      jpg = "/images/GB-TOCgreenAboutOn.jpg";
    } else {
      jpg = "/images/GB-TOCgreenAboutOff.jpg";
    }
   document.getElementById('TOCabout').src = jpg; 
  } 

  if (category == '4teachers') {
    if (onOrOff == 'on') {
      jpg = "/images/GB-TOCgreen4teachersOn.jpg";
    } else {
      jpg = "/images/GB-TOCgreen4teachersOff.jpg";
    }
   document.getElementById('TOC4teachers').src = jpg; 
  }

  if (category == 'contact') {
    if (onOrOff == 'on') {
      jpg = "/images/GB-TOCgreenContactOn.jpg";
    } else {
      jpg = "/images/GB-TOCgreenContactOff.jpg";
    }
   document.getElementById('TOCcontact').src = jpg; 
  }
  return true;
}