16. HTML 4.01<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">XHTML 1.0<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">HTML5<!DOCTYPE html>伯斯塔尔法则,浏览器接收时必须足够开放向后兼容Doctype是否为了浏览器而写?