Service Updates > add `NO_SERVICE` effect

[mmathieum]

App needs to know if a service update effect is NO_SERVICE to strikethrough time like 00:00 in the UI.

Information probably only available in GTFS-RT service alerts effect doc

Needed for:

• POI (& Schedule) screen > schedule (times) > show service updates UI ⚠️ ℹ️ mtransit-for-android#157

---

Related to:

• GTFS-RT alerts as NO_SERVICE but no CANCELLED/DELETED trip updates #90