Audience is an opaque reference to the segment this campaign targets. It is stored and echoed but not yet handed to the executors — a channel targets through the provider account it runs under — so it is documentation for now. Absent when never set.
Channels are the fan-out targets, at most one per kind and at most 12, each carrying its own post-launch state. Empty means nothing to launch, which is what makes a launch of this campaign a 400.
Content is the ordered creative set, at most 32, empty entries dropped. Content0 is the creative that runs; the rest are A/B variants a wired experiment can assign per launch.
ID is the campaign's server-minted handle — "cmp_" and 128 random bits — and the id every other campaign call is addressed by. Never read off the wire: a create that sends one has it ignored.
ScheduleAt is when the campaign should run, in unix seconds. 0 (absent) means launch immediately. It is passed to each executor; nothing in this service wakes up to launch it for you.
Status is the lifecycle state, server-owned and never accepted from a caller. Four values actually occur: draft (inert and fully mutable — nothing is sent and no budget is committed), live, paused and failed. After a fan-out live means AT LEAST ONE channel launched — read the channel rows for the rest — and failed means none did.
