e a new role)

  Since these are only per-file, better use Sphinx' facilities for setting the
  :confval:`default_role`.

Do *not* use the directives :dudir:`sectnum`, :dudir:`header` and
:dudir:`footer`.

Directives added by Sphinx are described in :ref:`sphinxmarkup`.

Basically, a directive consists of a name, arguments, options and content. (Keep
this terminology in mind, it is used in the next chapter describing custom
directives.)  Looking at this example, ::

   .. function:: foo(x)
                 