The HTML5 WD states (section 1.1.1[1]) that the format is meant to be as
much backwards-compatible as possible. With a little change to section
8.1.1[2], HTML5 could, in fact, be fully backwards compatible.
The current version (4.01) of HTML requires[3] documents to start with
this DOCTYPE line:
<!doctype html public "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd";>
But that line is not allowed in the latest draft of version 5. Why not?
The corresponding DOCTYPE lines from earlier versions of HTML can also
be allowed. I think most documents that conformed to HTML when those
DOCTYPE lines were current are still valid in HTML5 (once HTML5 allows
those DOCTYPEs.)
[1] http://www.w3.org/TR/2008/WD-html5-20080122/#relationship
[2] http://www.w3.org/TR/2008/WD-html5-20080122/#the-doctype
[3] http://www.w3.org/TR/1999/REC-html401-19991224/struct/global.html#h-7.2
Bert
--
Bert Bos ( W 3 C ) http://www.w3.org/
http://www.w3.org/people/bos W3C/ERCIM
[EMAIL PROTECTED] 2004 Rt des Lucioles / BP 93
+33 (0)4 92 38 76 92 06902 Sophia Antipolis Cedex, France
