Cool. It looks like the one place I'd seen these terms used is a subcategory of one of a few different but related uses. https://en.wikipedia.org/wiki/Covarian

Cool. It looks like the one place I'd seen these terms used is a subcategory of one of a few different but related uses. https://en.wikipedia.org/wiki/Covariance_and_contravariance https://en.wikipedia.org/wiki/Covariance_and_contravariance