oh, I probably can answer your question to that.
There are various HTML document out there, which can be identified by looking at the very beginning of the code.
www.programmerstalk.net for example, when you do view source on the home page. You will see something like this in the beginning of the document:
Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
that means that we're currently using HTML version XHTML transitional 1.0, and as you see we're using EN as the language. There are other that using Strict instead of transitional, which forced more to the XHTML version than HTML. <br /> is XHTML version of HTML
hopefully that helps..!
btw.. those are not PHP, those are HTML
