Re: define "out-of-tree"?

[Stephen Leake <stephen_leake@stephe-leake.org>]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> The main problem with that approach is that it wouldn't really work for
> out-of-tree packages, since introducing something like that requires
> Emacs Lisp engine level changes, I think.

I've never seen the term "out-of-tree" used this way before; I have seen
it when talking about compiling outside the source tree.

In most of this discussion, it seems to mean "with older versions of
Emacs", but sometimes it seems to mean something else. Hmm, perhaps
"with other than current Gnu Emacs implementations of lisp" (ie,
XEmacs)?

In either case, the phrase "out-of-tree" seems an odd term for that
meaning.

Could you define it for me, please?

A complete etymology would be nice, too :).

-- 
-- Stephe