name for a mutually inclusive relationship

[2QdxY4RzWzUUiLuE at potatochowder.com]

On 2021-02-24 at 13:05:05 -0800,
Ethan Furman <ethan at stoneleaf.us> wrote:

> entangled (none or all):
> 
>    image size override:  height   width

IMO, that's *one* option (-s 640x480 or -s 640,480), not two.  In
argparse/optparse terms, a required argument with a custom type.

(OTOH, in a GUI, it'd be two separate mandatory text fields, both
controlled (i.e., enabled or disabled) by one checkbox.)