Segments
A segment is who a group-scoped event is about. A static segment keeps a list you add to; a dynamic segment holds whoever's attributes contain its filter, so nobody keeps it up. Beside the segments somebody keeps are temporary lists, picked by a person for one send: you can see them, but a key cannot change one and an event cannot name one. In the Subscription business pack a segment is, for example, “Annual plans”.
DELETETake someone out of a segment
Requires groups:write. Named by Raven's id for the subscription or customer, not by a membership id. Membership is who is in the segment now, so this really removes; what was sent to them while they were in it is untouched. The one DELETE in the API.
204 with no body. 404 when they are not in this segment. 409 on a temporary list.
None: success is 204. On failure the body is { error, code }.