html header format - DTD, DOCTYPE, lang
Recommended list of Doctype declarations you can use in your Web document - http://www.w3.org/QA/2002/04/valid-dtd-list.html
HTML 4.01
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">
<html lang="ko"> 한국어
<html lang="en"> 영어
<html lang="ja"> 일본어
<html lang="zh"> 중국어
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Type" content="text/html; charset=euc-kr">
<link rel="stylesheet" type="text/css" href="default.css">
XHTML 1.0
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!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" xml:lang="ko" lang="ko"> 한국어
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 영어
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="ja" lang="ja"> 일본어
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh" lang="zh"> 중국어
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" type="text/css" href="default.css" />
<script type="text/javascript" href="default.js"></script>
HTML ISO Language Code Reference - http://www.w3schools.com/tags/ref_language_codes.asp