What's the line setting vim option at the bottom of a text file called?

Question

The line looks like this

.. vim: set ft=help norl ts=8 tw=78 et :

And appears at the bottom of some text files, such as vim documentation.<

Answer 1

It is called a modeline.

See :help modeline for more information.

Basically, it is a way to tell Vim how to render a text file.