What does a pipe (|) do in a CSS selector?

Question

I found the following definition in a CSS stylesheet :

*|*:link {color:#ff00ff;}

What\'s the use of the |? Is it

Answer 1

It separates namespace and element name.

Unless a default namespace has been defined, *|*:link is a complicated way of writing *:link or just :link.

In an XML document, you could have the following: