> before, didn't they? Is this implying that now lowercase is preferred?

I dug this up from the repo:

   org-element: Prefer lower case letters for blocks and keywords

   https://code.orgmode.org/bzg/org-mode/commit/13424336a6f30c50952d291e7a82906c1210daf0

So the answer is yes. Also the begin/end pairs are lowercase hardcoded
in org-tempo.el.

This is a problem for available (ya)snippet databases. I've reported
it in https://github.com/AndreaCrotti/yasnippet-snippets/issues/303,
requesting an update. But I guess people will prefer uppercase for a
time so I'm now sure how should they should cope with the transition.

Best regards
--
Carlos

>
> Regards
> --
> Carlos