function nav_query(){
// At load, query the current page for its navigational links
// and update the book's navigational buttons

  var nav1=document.links[0].href;  // link for next
  var nav2=document.links[1].href;  // link for up
  var nav3=document.links[2].href;  // link for previous

  var lnk1=document.images[0].src;  // image for next
  var lnk2=document.images[1].src;  // image for up
  var lnk3=document.images[2].src;  // image for previous

  if(lnk1.match(/next_motif\.gif/)){
    parent.next_update(nav1);
    if(lnk2.match(/up_motif\.gif/))
      parent.up_update(nav2);
    else
      parent.up_update("up_gr");
    if(lnk3.match(/previous_motif\.gif/))
      parent.previous_update(nav3);
    else
      parent.previous_update("previous_gr");
  }
  else{
    parent.next_update("next_gr");
    if(lnk2.match(/up_motif\.gif/))
      parent.up_update(nav1);
    else
      parent.up_update("up_gr");
    if(lnk3.match(/previous_motif\.gif/))
      parent.previous_update(nav2);
    else
      parent.previous_update("previous_gr");
  }
}

function next_update(w){
// Update the book's "next" navigation button

  var navimg=parent.book_nav.document.images;
  for(i=0; i<navimg.length; i++){
    if(navimg[i].name=="bnext"){
      if(w!="next_gr"){
        navimg[i].src="images/t4b_up.gif";
        parent.book_nav.document.links[i-1].href=w;
      }
      else{
        parent.book_nav.document.images[i].src="images/t4b_gr.gif";
        parent.book_nav.document.links[i-1].href="#";
      }
    }
  }
}

function up_update(w){
// Update the book's "up" navigation button

  var navimg=parent.book_nav.document.images;
  for(i=0; i<navimg.length; i++){
    if(navimg[i].name=="bup"){
      if(w!="up_gr"){
        navimg[i].src="images/t3_up.gif";
        parent.book_nav.document.links[i-1].href=w;
      }
      else{
        parent.book_nav.document.images[i].src="images/t3_gr.gif";
        parent.book_nav.document.links[i-1].href="#";
      }
    }
  }
}

function previous_update(w){
// Update the book's "previous" navigation button

  var navimg=parent.book_nav.document.images;
  for(i=0; i<navimg.length; i++){
    if(navimg[i].name=="bprev"){
      if(w!="previous_gr"){
        navimg[i].src="images/t4a_up.gif";
        parent.book_nav.document.links[i-1].href=w;
      }
      else{
        parent.book_nav.document.images[i].src="images/t4a_gr.gif";
        parent.book_nav.document.links[i-1].href="#";
      }
    }
  }
}

function preloadImages() {
  if (document.images) {
    var imgFiles = preloadImages.arguments;
    if (document.preloadArray==null) 
      document.preloadArray = new Array();
    var i = document.preloadArray.length;
    with (document) for (var j=0; j<imgFiles.length; j++){
      preloadArray[i] = new Image;
      preloadArray[i++].src = imgFiles[j];
    }
  }
}

function swapImgRestore() {
  if (document.swapImgData != null){
    for (var i=0; i<(document.swapImgData.length-1); i+=2){
      if(!document.swapImgData[i].src.match(/t3_gr/)){
      if(!document.swapImgData[i].src.match(/t4a_gr/)){
      if(!document.swapImgData[i].src.match(/t4b_gr/)){
        document.swapImgData[i].src = document.swapImgData[i+1];
      }}}
    }
  }
}

function swapImage() {
  var i;
  var j=0;
  var objStr;
  var obj;
  var swapArray=new Array;
  var oldArray=document.swapImgData;

  for (i=0; i < (swapImage.arguments.length-1); i+=2) {
    objStr = swapImage.arguments[i];
    obj = eval(objStr);
    swapArray[j++] = obj;
    swapArray[j++] = (oldArray==null || oldArray[j-1]!=obj)?obj.src:oldArray[j];
    obj.src = swapImage.arguments[i+1];
  }
  document.swapImgData = swapArray; //used for restore
}

function checkFrameset() {
// If the current page has no other parent, load index.html plus a search string
// passing the current page URL as a search parameter.
   var minNav3 = (navigator.appName == "Netscape" && 
      parseInt(navigator.appVersion) >= 3)
   var minIE4 = (navigator.appName.indexOf("Microsoft") >= 0 && 
      parseInt(navigator.appVersion) >= 4)
   var minDOM = minNav3 || minIE4   // Baseline DOM required for this function 
   var isNav4 = (navigator.appName == "Netscape" && 
      parseInt(navigator.appVersion) == 4)
   if (parent == window) {
      // Don't do anything if running NN4 so that the frame can be printed on its own.
      if (isNav4 && window.innerWidth == 0) {
         return
      }
      if (minDOM) {
         // Use replace() to keep current page out of history.
         var sl = location.pathname;
         var node = sl.match(/\w+\.html/);
         location.replace("index.html?" + node);
      } else {
         location.href = "index.html?" + node;
      }
   }
}