Integer. These can be listed and described with the
routes function.
route_type
A route type which can be provided either as a non-negative
integer code, or as a character: "Tram", "Train", "Bus", "Vline" or "Night
Bus". Character inputs are not case-sensitive. Use the
route_types function to extract a vector of all route types.
direction_id
Optionally filter by a direction ID. These can be
obtained with the directions_on_route function.
user_id
Integer or character. A user ID or devid provided by Public
Transport Victoria. Refer to ?ptvapi for more details.
api_key
Character. An API key, with dashes, provided by Public
Transport Victoria. Refer to ?ptvapi for more details.