name for a mutually inclusive relationship

[Chris Angelico]

On Thu, Feb 25, 2021 at 4:06 PM Avi Gross via Python-list
<python-list at python.org> wrote:
>
> Is there a more general idea here? How about asking for a control that
> internally manages N items and requires exactly M of them before the entry
> is accepted when you click? The case being discussed sort of wants N out of
> N, or nothing.
>

YAGNI.

ChrisA