Site pages declared as XHTML document:
<!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">
is it safe to change it to HTML5:
<!DOCTYPE html>
<html>
and is there any point in it considering that the project is quite large?