Hvem kan forklare mig hvorfor følgende Jscript kan ses i NS 4.7, men ikke i 6.01?

<SCRIPT LANGUAGE=\"JavaScript\">
<!-- Original:  Mike McGrath (mike_mcgrath@lineone.net) -->
<!-- Web Site:  http://website.lineone.net/~mike_mcgrath/ -->

<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->

<!-- Begin
var msg = \"This page requires version 4 or later of\\n Netscape Navigator or Internet Explorer\"
var dyn = (document.layers || document.all) ? true : alert(msg);
var nav = (document.layers) ? true : false;
var iex = (document.all) ? true : false;
var lft = 10; // (window.screen.width/2);
var pos = 10;  // initial top position
var stp = 10;    // step increment size
var spd = 150;  // speed of increment
var upr = -390;  // upper limiter
var lwr = 100;  // lower limiter
var tim;        // timer variable
function scroll_up() {
if(pos > upr) pos -= stp;
do_scroll(pos); 
tim = setTimeout(\"scroll_up()\", spd);
}

function scroll_dn() {
if(pos < lwr) pos += stp;
do_scroll(pos);
tim = setTimeout(\"scroll_dn()\", spd);
}

function do_scroll(pos) {
if(iex) document.all.divTxt.style.top = pos;
if(nav) document.divTxt.top = pos;
}

function no_scroll() {
clearTimeout(tim);
}

var divTop_content=\"\";

if(iex) document.write(\'<DIV ID=\"divTop\" STYLE=\"position:absolute; top:0; left:\'+lft+\'; width:300; height:100; background-color:white; z-index:3\">\'+divTop_content+\'</DIV>\');
if(nav) document.write(\'<LAYER ID=\"divTop\" position=\"absolute\" top=\"0\" left=\"\'+lft+\'\" width=\"300\" height=\"100\" bgcolor=\"white\" z-index=\"3\">\'+divTop_content+\'</LAYER>\');

var divBtm_content =(\'<HR><TABLE BORDER=\"0\" WIDTH=\"100%\"><TR><TD ALIGN=\"left\"><A HREF=\"java script://\" ONMOUSEOVER=\"scroll_up()\" ONMOUSEOUT=\"no_scroll()\">SCROLL DOWN</A></TD><TD ALIGN=\"right\"><A HREF=\"java script://\" ONMOUSEOVER=\"scroll_dn()\" ONMOUSEOUT=\"no_scroll()\">SCROLL UP</A></TD></TR></TABLE>\');

if(iex) document.write(\'<DIV ID=\"divBtm\" STYLE=\"position:absolute; top:350; left:\'+lft+\'; width:300; height:800; background-color:white; z-index:2\">\'+divBtm_content+\'</DIV>\');
if(nav) document.write(\'<LAYER ID=\"divBtm\" position=\"absolute\" top=\"350\" left=\"\'+lft+\'\" width=\"300\" height=\"800\" bgcolor=\"white\" z-index=\"2\">\'+divBtm_content+\'</LAYER>\');

var divTxt_content = (\'<b>These are ACTUAL letters to \"Dear Abby\"</b><hr><P><br>Dear Abby, I have a man I never could trust.  He cheats so much on me I\\\'m not even sure this baby I\\\'m carrying is his.<P><br>Dear Abby, I am a twenty-three year old liberated woman who has been on the pill for two years.  It\\\'s getting expensive and I think my boyfriend should share half the cost, but I don\\\'t know him well enough to discuss money with him.<P>Dear Abby, I suspected that my husband had been fooling around, and when I confronted him with the evidence he denied everything and said it would never happen again.<P>Dear Abby, Our son writes that he is taking Judo.  Why would a boy who was raised in a good Christian home turn against his own?<P>Dear Abby, I joined the Navy to see the world.  I\\\'ve seen it.  Now how do I get out?<P>Dear Abby, I was married to Bill for three months and I didn\\\'t know he drank until one night he came home sober.<P>Dear Abby, My forty-year-old son has been paying a psychiatrist $50 an hour every week for two-and-a-half years.  He must be crazy.<P>Dear Abby, I have always wanted to have my family history traced, but I can\\\'t afford to spend a lot of money to do it.  Any suggestions?  Signed, Sam Dear Sam, Yes.  Run for public office.<P>\'); 

if(iex) document.write(\'<DIV ID=\"divTxt\" STYLE=\"position:absolute; top:100; left:\'+lft+\'; width:300; font-family:verdana; font-size:10pt; background-color:white; z-index:1\">\'+divTxt_content+\'</DIV>\');
if(nav) document.write(\'<LAYER ID=\"divTxt\" position=\"absolute\" top=\"100\" left=\"\'+lft+\'\" width=\"300\" font-family=\"verdana\" font-size=\"10pt\" bgcolor=\"white\" z-index=\"1\">\'+divTxt_content+\'</LAYER>\');
//  End -->
</script>


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