[Kevin WS]

I think that your explanation is clear enough Elliot¡

In other English speaking countries vestibules are also called "corridor connections" and "gangway connections".

Vestibule is the term used in India as well.

Indian Railways do have some general rules regarding these, and advise as follows....

"Vestibules......

- Help the Pantry Car staff to reach both ends of the rake
- In case of stops with smaller duration, vestibule coaches are advantageous as the passenger can board coach and can reach his coach/berth.
- Vestibules are not provided to the coaches at the end.
- Vestibules are not provided to the last coach of each class, to curb the movement between the coaches of different classes to avoid misuse.
- There may not be a vestibule between S1(Sleeper coach) and B1/A1(2AC and 3AC) coaches, to avoid unauthorized access.
- Vestibules are never provided to any Unreserved, SLR and Chair Car coaches
- In all trains the UR coaches are not connected to the other coaches of the train by vestibules, to prevent passengers holding unreserved tickets from entering reserved coaches.
- AC First Class and AC 2 tier coaches vestibules are closed during night time from other coaches of the train, to prevent unauthorised passengers entering AC class coaches."

All Shatabdis, Duranto and Rajdhani trains have vestibules.