Versions and publishing
Publishing saves a composition as a numbered version that never changes. Outputs play versions, so editing never touches what's on air.
Publish
Choose Publish in the editor and add a short note about what changed. The new version is numbered one after the last. Operators can't publish; everyone else can.
Outputs
Each output plays one version of one composition. Choose it on the Outputs page, not in the control room, so nobody switches versions mid-show by accident.
When a newer version is published, the output offers it. Moving an output to another version of the same composition keeps what's on air, its data and its instances, and the new design takes over at once. Linking a different composition starts again with nothing on air.
From code, Get the output's composition tells you when a newer version is out. Publishing and moving an output to it are done in Airframe, so a script can't change the show's design mid-broadcast.