From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thorsten Jolitz <tjolitz@gmail.com>
Subject: Re: What does the _ in `(defun org-element-section-parser (_) ...)'
 stands for?
Date: Wed, 10 Feb 2016 21:13:04 +0100
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John Kitchin <jkitchin@andrew.cmu.edu> writes:

> I guess it is a required signature for the function (i.e. some other
> function will call it with some argument), and _ indicates it is not
> used in the body. If you were to give it the arg a name, then checkdoc
> would complain about it not being in the docstring.

Sounds reasonable, thanks for the explanation.
But it does not seem to be a true guess, I tried it out with:

#+BEGIN_SRC emacs-lisp
(defun my-foo (_)
  "Hello World.
Argument _ unknown argument."
  (+ 1 1))
#+END_SRC

and checkdoc asked me to add the "Argument ..." part for "_" to the docstring.

I don't remember that I've seen this before, so maybe this is a rather new
feature/convention?

> Thorsten Jolitz writes:
>
>> Hi List,
>> just out of curiosity, a few functions in org-element.el contain _ in
>> their parameter list, but its not used in the body.
>> What does it stand for?
>
>
> --
> Professor John Kitchin
> Doherty Hall A207F
> Department of Chemical Engineering
> Carnegie Mellon University
> Pittsburgh, PA 15213
> 412-268-7803
> @johnkitchin
> http://kitchingroup.cheme.cmu.edu
>
>

-- 
cheers,
Thorsten