name for a mutually inclusive relationship

[Tim Chase]

On 2021-02-24 08:12, Ethan Furman wrote:
> I'm looking for a name for a group of options that, when one is
> specified, all of them must be specified.
[snip]
> - ???: a group of options where, if one is specified, all must be
> specified (mutually inclusive)
[snip]
> Is there a name out there already to describe that concept?

For two items, the XNOR logical operator (effectively a "not (a xor
b") has the desired truth-table.

  https://en.wikipedia.org/wiki/Xnor

sometimes called a "logical biconditional"

  https://en.wikipedia.org/wiki/Logical_biconditional

But in more human terms, the common phrase "all or nothing" seems to
cover the concept pretty well.

-tkc