What can cause downcasing in Emacs Lisp code?

[Jean Louis]

I have noticed few times in last months, including today, that I find
some strings in Emacs Lisp code downcased. I cannot know what is
happening, as it is maybe something I press by mistake, but I cannot
find what. I don't mark things and don't use `downcase-region'

As usually all of the Emacs Lisp is anyway downcased, I can only
observe strings within quotes to be downcased, but maybe some 

Then I can observe instead of this:

(defun hlink-yank-note (&optional id)
  "Kill the note and yanks into the other window"
  (interactive)
  (when-tabulated-id "hlinks" id
    (hyperscope-ring id)
    (hlink-yank-note-1 id)))

I can observe following "kill" instead of "Kill"

(defun hlink-yank-note (&optional id)
  "kill the note and yanks into the other window"
  (interactive)
  (when-tabulated-id "hlinks" id
    (hyperscope-ring id)
    (hlink-yank-note-1 id)))

And that downcasing makes me again edit so much more. I do not know
how I invoke that.

Maybe somebody knows?



Jean