Doctypes that work

So what DOCTYPEs should we use? Glad you asked. The following complete DOCTYPEs are the ones we need:

XHTML 1.1 DTD

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

XHTML 1.0 Strict, Transitional, Frameset

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

HTML 4.01 Strict, Transitional, Frameset

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN"
"http://www.w3.org/TR/html4/frameset.dtd">
<html>

Note that there is also a schema based xhtml doctype (I took it from oXygen xml editor). But is it well supported ?

XHTML 1.1 schema

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3.org/1999/xhtml http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd"
xmlns="http://www.w3.org/1999/xhtml">
<head>

There is also a new html norm : html5

BOYCOT IT !!!

See why you have to boycott it (in English) http://eric.van-der-vlist.com/blog/2008/01/31/html-5-turns-documents-into-applications/

French translation http://xmlfr.org/actualites/decid/080131-0001

HTML5

<!DOCTYPE html>