Are you looking for the platform the train departs from?
Where is the train that leaves Stansted Airport that arrives at 13:15? No, sorry. I would like to book a train from Stansted Airport to Cambridge, please.
{"__type": "Request", "service": "train", "values": ["departure"]}
{"__type": "Inform", "entity": {"__type": "Train", "arrive by": "12:52", "day": "Monday"}}
I have one on Monday that arrives at 12:52