Only used together with Watch label. When on, a run also re-delivers an opportunity you already have if its closing date, forecast-vs-posted status, opportunity status (posted/closed/archived), award ceiling/floor, last-updated date or eligibility text has changed since you last saw it -- e.g. a deadline extension, a forecast turning into a real posted opportunity, an opportunity closing early, or a revised funding range. The last four are only watched when Enrich is on (the default), since they only exist on the enriched detail record. Charged at the same per-row price as a new opportunity. Each changed row is tagged with _watchChangeType (one or more of closeDate, docType, oppStatus, awardCeiling, awardFloor, lastUpdatedDate, applicantEligibilityDesc) plus the previous value(s) under _watchPrevious. IMPORTANT: do not also FILTER on a field you want change alerts on -- the change itself would drop the opportunity out of your match set and it could never be reported. In particular the default Opportunity statuses (forecasted + posted) hide every posted->closed transition: set all four statuses to catch closures. Widening is free to backfill (a new filter set gets a free 0-row baseline run). The run logs a warning and fills RUN_SUMMARY.watchChangeBlindFilters whenever a filter is hiding changes this way. Off by default so existing watches keep their current behaviour.