NPR's Code Switch podcast had an episode a few years ago on this, which they call the explanatory comma: https://www.npr.org/2016/12/14/504482252/-hold-up-time-

NPR's Code Switch podcast had an episode a few years ago on this, which they call the explanatory comma: https://www.npr.org/2016/12/14/504482252/-hold-up-time-for-an-explanatory-comma https://www.npr.org/2016/12/14/504482252/-hold-up-time-for-a... It gets at what you assume about your audience when you include vs. don't include these. I'm sometimes amused by what gets the explanatory comma in The New Yorker. I recall one issue where they included one for what an MLA citation was. But in the same issue assumed familiarity with someone like Jacques Derrida and their ideas. (This probably wasn't the exact example, but it was close to this.)