This page provides a list of realtime transit terms and definitions to help transit partners and data aggregators use the terms consistently across multiple documents or user interfaces.
| Terms | |
|---|---|
| Carriage | A separate section of a train that carries passengers. |
| Entity | A distinguishable object that represents a real-world existence, such as a vehicle, trip, or stop. Entities are identifiable with a unique ID, and each entity type has a set of fields that describe it. |
| Header | A record that provides metadata about a feed, such as its version and timestamp. |
| Message | A record that contains data about a particular entity. Messages are included in feed messages, and they provide information about the entities in the feed. |
| Realtime feed | A file that complies with the GTFS-realtime format and provides current information about the transit service. The file's contents cover trip updates, service alerts, or vehicle positions |
| Service alerts | Alerts that provide passengers with updates when there’s a disruption on the transit network. |
| Trip updates | Updates about the delays or cancellations of individual trips. |
| Vehicle positions | Information about the current location of a particular vehicle. |