The term 'retention margin' doesn't seem like a commonly-used term (according to a quick Google search, anyway). The definition seems identical to the commonly

The term 'retention margin' doesn't seem like a commonly-used term (according to a quick Google search, anyway). The definition seems identical to the commonly-used term 'contribution margin', i.e. revenue less variable costs. https://en.wikipedia.org/wiki/Contribution_margin https://en.wikipedia.org/wiki/Contribution_margin