On Usenet, a posting generated in response to another posting (as opposed to a reply, which goes by e-mail rather than being broadcast). Followups include the ID of the parent message in their headers; smart news-readers can use this information to present Usenet news in "conversation" sequence rather than order-of-arrival. See thread.
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Nearby terms: fold case « folder « FOLDOC « followup » font » fontology » foo