Date: 03/17/06 (Java Web)    Keywords: browser, css, html

In order to deal with both old tag soup written to old browser quirks and new standards-compliant pages, Mozilla (and Mozilla-based browsers), Mac IE 5, Windows IE 6, Safari, Opera 7 and Konqueror 3.2 have two main layout modes. In one mode the layout engine attempts to render conforming pages according the CSS and HTML [...]

Source: http://blog.taragana.com/index.php/archive/browser-quirks-mode-activation-table/