However, most clients support only a handful of HTML Level 3 features at the time of this writing. The most commonly implemented major feature is table support. If you have access to a Unix system with the X Window System installed, you can try out many features of HTML Level 3 using the experimental Arena browser.
You can access information about new developments
in HTML at the CERN server
(at the URL
http://www.w3.org/hypertext/WWW/MarkUp/MarkUp.html
).
(HTML Level 1 is the original version. HTML Level 2 is essentially the same, but with the addition of forms.)