TripDescriptor.start_date matching between GTFS-RT + GTFS-static

Hi everyone!

I have a question regarding the `TripDescriptor.start_date`. Currently, the documentation tells me this:

https://gtfs.org/realtime/reference/#message-tripdescriptor

Two questions:

- Since the `start_date` timezone is not directly specified, I assume that it's in the corresponding agency timezone of the trip? Some fields in the specification are explicitly specified to be in UTC. For the rest I can assume that they refer to the GTFS-static local times? (to be translated like the GTFS-static data as described [here](https://gist.github.com/derhuerst/574edc94981a21ef0ce90713f1cff7f6)).
- What happens in case the first departure time is greater than `24:00:00`? The start date is the one specified in the `service_id` or the "real" start date (which would be for example on the next day)?

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### Example:

***`calendar_dates.txt`***
```
service_id,date,exception_type
S,20190331,1
```

**`trips.txt`**
```csv
route_id,service_id,trip_id,trip_headsign,block_id
R_RE1,S,T_RE1,RE 1,1
R_RE2,S,T_RE2,RE 2,1
```

**`stop_times.txt`**
```csv
trip_id,arrival_time,departure_time,stop_id,stop_sequence,pickup_type,drop_off_type
T_RE1,00:00:00,00:00:00,A,1,0,0
T_RE1,48:30:00,48:30:00,B,2,0,0
T_RE2,48:30:00,72:30:00,B,1,0,0
T_RE2,72:30:00,96:30:00,C,2,0,0
```

Now the first departure time of trip `T_RE2` would be on

| from `service_id` | UTC First Departure translated with offset at noon `-02:00` | Local First Departure |
|------------------------|-----------------------------|-----------------------------|
| 2019-03-31 | 2019-04-01 | 2019-04-02 |

I would guess that GTFS-RT is supposed to give me the date from `service_id` (2019-03-31) to refer to the trip. However, both other options would also be reasonable in a way.

----

I have not been able to get this information from the specification. Can someone please clarify how to handle these cases?