Appendix D Comparison of HTML 4, XHTML, and HTML 5^623HTML 5
<!doctype html>
HTML 5 (XHTML Syntax)
<!doctype html>
Optional if the document is servedas XML
Required if the document is served as text/html
The Tag
XHTML requires that the root element (immediately after the DTD) is an tag
that refers to the XML namespace. HTML 4 has no such requirement. To assist the
interpreting of page content by search engines and screen readers, use the lang attribute
to indicate the spoken language of the Web page content. See http://www.w3.org/TR/
REC-html40/struct/dirlang.html#adef-lang.
HTML 4
XHTML
HTML 5 (HTML Syntax)
HTML 5 (XHTML Syntax)
D.3 Uppercase versus Lowercase
The HTML 4 standard recommends that tags and attributes use uppercase. The
XHTML standard follows XML syntax, which requires lowercase.
HTML 4