Get info about a single arrival and departure for a stop
<response> <version>2</version> <code>200</code> <text>OK</text> <currentTime>1270614730908</currentTime> <data class="entryWithReferences"> <references>...</references> <entry class="arrivalAndDeparture"> <!-- See documentation for the arrivalAndDeparture element, linked below --> </entry> </data> </response>
The key here is uniquely identifying which arrival you are interested in. Typically, you would first make a call to arrivals-and-departures-for-stop to get a list of upcoming arrivals and departures at a particular stop. You can then use information from those results to specify a particular arrival. At minimum, you must specify the trip id and service date. Additionally, you are also encouraged to specify the vehicle id if available to help disambiguate between multiple vehicles serving the same trip instance. Finally, you are encouraged to specify the stop sequence. This helps in the situation when a vehicle visits a stop multiple times during a trip (it happens) plus there is performance benefit on the back-end as well.
The method returns an <arrivalAndDeparture/> element as its content.