The Service Interface for Real Time Information gold SIRI is an XML protocol to allow distributed computers to exchange real time information about public transport services and vehicles.
The protocol is a CEN technical specification, with initial participation Developed by France, Germany ( Verband German Transport ), Scandinavia, and the UK ( RTIG )
SIRI is based on the Transmodel abstract model for public transport information, and includes a general purpose model, and an XML schema for public transport information.
A SIRI White Paper is available for further information on the protocol  .
SIRI is a pioneer in the field of information and communication technologies. The information can be used for many different purposes, for example:
- To provide real time-departure from stop information for display on stops, internet and mobile delivery systems;
- To provide real-time progress information about individual vehicles;
- To manage the movement of buses roaming between areas covered by different servers;
- To manage the synchronization of guaranteed connections between fetcher and feeder services;
- To exchange planned and real-time timetable updates;
- To distribute status messages about the operation of the services;
- To provide performance information to operational history and other management systems.
SIRI includes a number of optional capabilities. Different countries may specify a country of the SIRI capabilities that they wish to adopt.
Version 2.0 of SIRI  , representing the CEN documents as published, is currently available as a set of XSD files packaged as a zip file  .
SIRI is kept under an informal maintenance regime, with version control. Later versions of the schema are available at the same site, together with change notes.
Example of sites using SIRI
Different SIRI implementations are used in a number of sites globally
Europe and UK
- Leicester Travel: Real-time bus from SIRI-SM http://leicestertravel.info/
- Transport for London Incidents from SIRI-GMS  & Real-time data from LBS River http://www.tfl.gov.uk
- Norwegian Railway Administration: All train movements in Norway: http://bent.flyen.no/realtimeNorway
- Ruter / Trafikanten Oslo, Norway: Boats, buses, subway and trams in Eastern Norway http://ruter.no/en/Services/The-Realtime-System/
- Several other Norwegian systems support SIRI, for status: http://bent.flyen.no/realtimeNorway
- Västtrafik, PTA for western Sweden, uses SIRI ET and SX for real time information in the travel planner: http://reseplanerare.vasttrafik.se/bin/query.exe/en
- Traveline Scotland: SIRI-SX for disruption information http://www.travelinescotland.com
- Helsingin Seudun Liikenne, Finland uses siri vm http://dev.hsl.fi/
- New York City MTA BusTime – SIRI-SM and SIRI-VM – http://bustime.mta.info/wiki/Developers/Index
- Utah Transit Authority : http://developer.rideuta.com/StopMonitoringInstructions.aspx
- METRO (Houston, TX) : https://developer.ridemetro.apiphany.com/products
- Ningbo City – Buses, Real time traffic control systems with SIRI, stations and vehicles electronic devices 2011-2012 http://www.novasolution.com.hk
- Transport for New South Wales – SIRI-SX for disruption information: http://www.transportnsw.info
- Identification of Fixed Objects In Public Transport (IFOPT)
- Intermodal Journey Planner
- Transport standards organisations
- Jump up^ http://www.theregister.co.uk/2011/10/19/countdown_2/