var internal_lo_images;
  var internal_hi_images;
  var external_lo_images;
  var external_hi_images;
        
  function setup_internal_images(numberofreferences) {
        
      internal_lo_images = new Array(numberofreferences);
      internal_hi_images = new Array(numberofreferences);
      
      for (var i = 0;  i < numberofreferences;  i++) {
          internal_lo_images[i] = new Image();
          internal_lo_images[i].src = "../images.two.state/internallo.png";
          internal_hi_images[i] = new Image();
          internal_hi_images[i].src = "../images.two.state/internalhi.png";
      }
  }
    
  function internal_buttonhi(referencename) {
      var  INTERNAL_REFERENCE_LENGTH = "internalreference".length;
      var  referencestring =  referencename.substr(INTERNAL_REFERENCE_LENGTH);
      var  referencenumber =  parseInt(referencestring);
      referencenumber = referencenumber - 101;
      document[referencename].src = internal_hi_images[referencenumber].src;
  }
  
  function internal_buttonlo(referencename)   {
      var  INTERNAL_REFERENCE_LENGTH = "internalreference".length;
      var  referencestring =  referencename.substr(INTERNAL_REFERENCE_LENGTH);
      var  referencenumber =  parseInt(referencestring); 
      referencenumber = referencenumber - 101;
      document[referencename].src = internal_lo_images[referencenumber].src;
  }
  
  function setup_external_images(numberofreferences) {
      
      //  alert("setup_external_images called");
      
      external_lo_images = new Array(numberofreferences);
      external_hi_images = new Array(numberofreferences);
      
      for (var i = 0;  i < numberofreferences;  i++) {
          external_lo_images[i] = new Image();
          external_lo_images[i].src = "../images.two.state/externallo.png";
          external_hi_images[i] = new Image();
          external_hi_images[i].src = "../images.two.state/externalhi.png";
      }
  }
     
  function external_buttonhi(referencename) {
      var  EXTERNAL_REFERENCE_LENGTH = "externalreference".length;
      var  referencestring =  referencename.substr(EXTERNAL_REFERENCE_LENGTH);
      var  referencenumber =  parseInt(referencestring); 
      referencenumber = referencenumber - 101;
      document[referencename].src = external_hi_images[referencenumber].src;
  }
  
  function external_buttonlo(referencename)   {
      var  EXTERNAL_REFERENCE_LENGTH = "externalreference".length;
      var  referencestring =  referencename.substr(EXTERNAL_REFERENCE_LENGTH);
      var  referencenumber =  parseInt(referencestring); 
      referencenumber = referencenumber - 101;
      document[referencename].src = external_lo_images[referencenumber].src;
  }