It seems like this is nearly all possible already (see below). It is a
little wonky that you have to put text in a src txt block to achieve it,
but otherwise what is missing?

* Main document

See [[id:BAD97113-3561-4A4A-BA07-0CD5BF6BA35F][There is a reason we only
support two args]] (text to text) for notes about this function. The
addition is done in line [[(add)]] (text to code).

#+NAME: DOC-OF-ADD
#+BEGIN_SRC txt
"We use the function add to calculate the sum of two numbers."
#+END_SRC

#+NAME: ADD
#+BEGIN_SRC emacs-lisp -n -r :noweb yes :tangle test.el
(defun add (x y)
  <<DOC-OF-ADD>> ;; code to code
  ;; [[id:BAD97113-3561-4A4A-BA07-0CD5BF6BA35F][There is a reason we only
support two args]] code to text
  (+ x y) (ref:add)
  )
#+END_SRC

#+RESULTS: ADD
: add


** Notes

*** There is a reason we only support two args
    :PROPERTIES:
    :ID:       BAD97113-3561-4A4A-BA07-0CD5BF6BA35F
    :END:


John

-----------------------------------
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


On Sun, May 13, 2018 at 10:48 PM, Eric S Fraga <esflists@gmail.com> wrote:

> On Saturday, 12 May 2018 at 13:29, ZHUO QL (KDr2) wrote:
> > Hi all, I just post a proposal for orgmode on my website(generated by
> orgmode):
> > http://kdr2.com/tech/emacs/1805-proposal-org-ref-code-to-text.html .
> > Here is the source of the proposal:
> > # -*- mode: org; mode: auto-fill; -*-
> >
> > #+TITLE: Proposal for Orgmode: references from code to text.
> > #+AUTHOR: KDr2
>
> [...]
>
> > - Beside the ~NAME~, we could also support reference via the
> >   ~CUSTOM_ID~ property or anything else that can locate a text chunk.
> > - In the tangling process, we should do some kind of transformation of
> >   the target text, for example, escape the quote mark. A hook may be
> >   needed to let the user customize the transformation too.
> >
> > What do you think?
>
> I like the symmetry of having src reference text.  I guess, in what you
> propose above, that the text that would be incorporated would be a
> single element (in org parsing parlance) or else we would have to
> specify an extent in the link information.
>
> Are you able to implement something?  I would definitely help test it.
>
> --
> Eric S Fraga via Emacs 27.0.50, Org release_9.1.6-591-gee336b
>