How to address operational specific needs in a GTFS

### Introduce yourself

Hello,
I work for RATP DEV in France, I help affiliates with their AVLS and Passenger Services matters and sometimes ticketing when data expertise is required (about GTFS, GTFS-RT, Siri etc)

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For many years now, we deal with providers that will only accept GTFS as input data (ticketing systems and AVLS). GTFS is for passenger services and they are a lot of "non commercial" data needed to make the Systems work properly.

Eventually, we end up to bending the data and create many specific GTFS so the Systems can work.

I give you 3 examples:

1) For one of our affiliates, I have a GTFS with standard trips.trip_headsign (for the website, app etc), and we had to create a new one for Systems with external **destination sign code**.

2) 2 GTFS too for another affiliate: one with standard trips.block_id (sequential trips made using the same **vehicle**), another one specific required by System with sequential trips made using the same **driver**.

3) Ticketing System doesn't accept our GTFS because there is no stop_sequence = 1. Indeed, the first stop of the trip is non commercial (a parking lot). So in the GTFS, stop_sequence starts with stop_seq = 2. This is not a bug, this is real life.

How can we address operating systems needs with a GTFS that is build for passenger information?

Thanks you for your help and sorry if you already answered this question.
Regards
Emmanuelle