The plan, as published.

The one input that is already an open standard and already public. Everything in the operations files is measured against it.

stops
routes
scheduled trips across service patterns
stop times

A GTFS feed is a zip of plain text tables. This one runs from to , so it covers the whole sample month. It uses calendar_dates.txt alone, listing every service day explicitly, rather than a weekly calendar.txt.

Its service identifiers embed the board period that the operations files call TIME_TABLE_VERSION_NAME. That is the strongest link between the plan and the record; the trip identifier, which should be the link, is not.

stop_times.txt    50.8 MB   the plan, stop by stop
shapes.txt         5.9 MB   route geometry
trips.txt          2.4 MB   each run of a route
stops.txt        382 KB     where vehicles stop
calendar_dates     6 KB     which days service runs
routes.txt         4 KB     the lines riders know
feed_info, agency          who published it

The eight files. Sizes from the sample feed.

The feed carries more than one board period at once. The operations files for September use 24AU05.