//the number of images before the 1st menu tab
 //makes sure that the right images are loaded when highlighting and giving descriptions
 first_img=1; 

 //descrip_on keeps track of the descripton that is loaded -> set at top of each file 1.htm 2.htm etc...
 //0=page1
 //1=page2
 //2=page3
 //3=page4
 //4=first page (intro) 


//--------load "highlighted" tabs into memory---------
 tabon = new Array(4);
 
 for (i=0; i<4; i++)
  tabon[i]=new Image();
//--------------4 tabs tabon[0 1 2 3]-----------------


//------tab that it currently "on top"----------------
 ltab = new Array(4);
 
 for (i=0; i<4; i++)
  ltab[i]=new Image();
//---------------------------------------------------- 

//----------load description into memory--------------
 desc = new Array(4);
 
 for (i=0; i<4; i++)
  desc[i]=new Image();
//---------------4 desc [0 1 2 3]---------------------

 function on(image,file)
  {
   //look to off for descript of what image-first_img means
   if (descrip_on!=(image-first_img)) document.images[image].src=file;
   //document.images[4+first_img].src=desc[image-first_img].src;
  }

 function off(image,file)
  {
   //image = number of first_img + tab
   //therefore, if you take image-first_img, you get the tab
   if (descrip_on!=(image-first_img))
   {
    document.images[image].src=file;
   }

   if (descrip_on==4) document.images[4+first_img].src="images/desc.gif"
    else
     document.images[4+first_img].src=desc[descrip_on].src;
  }

 //when a new page is loaded, set up graphics
 function refresh()
 {
  if (descrip_on==4) document.images[4+first_img].src="images/desc.gif"

  if (descrip_on!=4)
   {
    document.images[descrip_on+first_img].src=ltab[descrip_on].src;
//    document.images[descrip_on+first_img].src="images/tabc1.gif";
    document.images[4+first_img].src=desc[descrip_on].src;
   }
 }