Hi GTFS-realtime community!
As per section 3 of the GTFS-realtime specification amendment process, I'm re-announcing PR #265 on the google/transit repo, which based on feedback from the community has new non-editorial changes to deprecate SKIPPED in favor of using MODIFIED and pickup and drop-off types instead.
The rationale here is to support a more detailed relationship of a vehicle to a scheduled stop beyond skipping it completely, such as a vehicle that may stop but won't pick up any new passengers ("drop-off only"), a technique used by agencies to regain time when running late or address a gap in service. This also will bring GTFS-realtime into consistency with GTFS-static's stop_times.txt.
Users will continue to be able to represent the SKIPPED scenario by specifying drop_off_type=NO_DROP_OFF and pickup_type=NO_PICKUP using StopTimeProperties.