VSTP
Also: very short term planning, short-notice train, short notice
A train planned too late to make it into the daily timetable file, sent out on its own instead.
VSTP stands for Very Short Term Planning. When a train is planned or changed at short notice, often on the day itself, there isn’t time to wait for the next timetable file, so the schedule is sent out on its own as a VSTP message.
Lots of freight trains are VSTP, and so are some passenger trains: replacements, extras and diversions.
In Trainiac
Trainiac reads VSTP schedules as they arrive. They often list only the stops, so Trainiac fills in the route between them along the track.