What is Corporate-action event, instrument lifecycle event?

A corporate-action event is the reference-data record of a corporate action: its kind (split, dividend, merger, spin-off), its terms, its effective date and its status (announced, confirmed, amended, cancelled), each change of status a new version with the time it became known. An instrument lifecycle event is any dated change to an instrument’s reference data: listing, rename, change of lot or tick, corporate action, delisting, expiry.