var fileext=".jpg";
  var rollsuff="-on";
 
  function checkVersion(){
    if (navigator.appVersion.charAt(0) > "2") {
      return true;
    } else {
      return false;
    }
  }
 
  function nametonumber(thename) {
    thename = "" + thename;
    var thenumber = -1;
    if(checkVersion()) {
      for(var i=0;i<document.images.length;i++){
        if(document.images[i].name == thename) {
          thenumber = i;
        }
      }
    }
    return(thenumber);
  }
 
  function addsuff(thestring) {
    thestring = "" + thestring;
    var extposition = thestring.indexOf(fileext,0);
    if(extposition != -1) {
      return(thestring.substring(0,extposition) + rollsuff + thestring.substring(extposition,thestring.length));
    } else {
      return(thestring);
    }
  }
 
  function delsuff(thestring) {
    thestring = "" + thestring;
    var dashrposition = thestring.lastIndexOf(rollsuff, thestring.length);
   if(dashrposition != -1) {
      return(thestring.substring(0,dashrposition) + thestring.substring(dashrposition+rollsuff.length,thestring.length));
    } else {
      return(thestring);
    }
  }
 
  function roll(imgname) {
    imgname = nametonumber(imgname);
    if(checkVersion() && (imgname >= 0)) {
      document.images[imgname].src = addsuff(document.images[imgname].src);
   }
  }
 
  function unroll(imgname) {
    imgname = nametonumber(imgname);
    if(checkVersion() && (imgname >= 0)) {
      document.images[imgname].src = delsuff(document.images[imgname].src);
   }
  }
 
  function getridofdashes(thename) {
 
    var thenewname=thename;
    while(thenewname.indexOf("-", 0) != -1) {
      thenewname=thenewname.substring(0, thenewname.indexOf("-", 0)) +
thenewname.substrin
g(thenewname.indexOf("-", 0)+1, thenewname.length);
    }
    return(thenewname);
  }
 
  function dopreload(thisimage) {
    if(thisimage != null) {
      var
tempname=getridofdashes(thisimage.substring(thisimage.lastIndexOf("/",thisimage.
length)+1, thisimage.length-fileext.length-rollsuff.length)+"rpreload");
      eval(tempname + " = new Image");
      eval(tempname + ".src" + " = thisimage");
    }
  }
 
  function checkpreload(thearray) {
    if(checkVersion()) {
      for(var i=0; i<thearray.length; i++) {
        dopreload(thearray[i]);
      }
    }
  }