Our vehicles have both private internal identifiers and public identifiers (on the exterior of the vehicle). For example, { "vehicle_id" = 3145, "vehicle_label" = 8006 }.

GTFS-realtime differentiates the two in the VehicleDescriptor messages as vehicle.id and vehicle.label, respectively, defining id as an internal identifier and label as the public facing identifier.

Describe the feature you want and how it meets your needs or solves a problem
As an implementer of TIDES data pipelines, and an analyst, I want to be able to lookup vehicle_locations using vehicle_id (using our internal identifier) when given the public identifier (vehicle_label) as seen on the inside and outside of our vehicles (e.g., 1651 in this photo: https://www.flickr.com/photos/metrotransitmn/52411904563/in/album-72177720302700615/).

Describe the solution you'd like

I would like to add vehicle_label to the vehicles table, linking the public and internal identifiers for our vehicles.

Describe alternatives you've considered

1. Maintain our own vehicle_label field as an extension.
2. Maintain an additional table with additional vehicle information not included in the spec.