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”.
POSTBuild segments from a subscription attribute
Requires groups:write. Makes one dynamic segment per value the subscriptions hold for the attribute you name — or one per combination, for up to four — and returns them. Safe after every import: what exists is left exactly as it is, and nothing is tidied away.
200 with the segments those attributes keep up, made now or before. 400 for a key no subscription can carry.
A bare JSON array. Each item is one segment: the same fields in every pack. Press Response on the sample to see one whole.
On failure the body is { error, code } instead.