尋找何時使用/不使用XHTML 1.0與XHTML 1.1 DTD的細節。Doctype聲明:XHTML 1.0與XHTML 1.1
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
參考鏈接:http://www.w3.org/QA/2002/04/valid-dtd-list.html