[whatwg] HTML Namespace Elements

[Mohammad Al Houssami (Alumni)]

Hello Everyone.

In the tokenizer specifications of the HTML5 parser the following is written :

"Otherwise, if there is a current node and it is not an element in the HTML 
namespace "
What does it mean ?
It is linked to this page http://www.w3.org/1999/xhtml which doesnt provide any 
information regarding the HTML namespace.

Any help is much appreciated.

Thanks :)