Every recorded save of the alert, with who saved it, when, and each setting's before and after. Newest first; the sort parameter is ignored. revision is an opaque ordering key shared by items saved in one request. Authors are masked: a Revenium staff member shows as Revenium Support, a change made by the system or recorded when change history began shows as Revenium (system), and an API key shows its name and owner. A deleted item's history stays readable. An unknown, malformed or unreadable id answers 404.