name for a mutually inclusive relationship

[Ethan Furman]

I'm looking for a name for a group of options that, when one is specified, all of them must be specified.

For contrast,

- radio buttons: a group of options where only one can be specified (mutually exclusive)
- check boxes:   a group of options that are independent of each other (any number of
                  them may be specified)

- ???: a group of options where, if one is specified, all must be specified (mutually
        inclusive)

So far, I have come up with:

- the Three Musketeers
- clique
- club
- best friends
- tight knit
- group

Is there a name out there already to describe that concept?

--
~Ethan~