The document should contain a valid “doctype” declaration¶
Severity code: Severe error
Each document must contain a valid doctype declaration..
Example¶
Wrong¶
<html>
Right¶
<!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:lang="en" lang="en">