What is kType ?

kType is mentionned when updating a vehicle `PUT /vehicles/{vehicleId}` or returned when querying a vehicle either with `GET /vehicles/{vehicleId}` or with ` GET /users/me/vehicles`

I don't know nothing (sic) about cars. But I can't find it either on the internet with a search engine. Except it was in API v1 and v3 already.