it seems that we can find out whether a webpage is CSS compliance mode / Quicks mode by

alert(document.compatMode);

can there be some method that can print out whether it is HTML 4.0 or 4.01, or whether it is XHTML 1.0 strict or loose? Looking at the page source can help but I just wonder if some browser like IE6 will force the iframed page to be the same doctype as the parent page. Thanks very much!