What does STP stand for please?
John Prytherch.
Presume in this context they are referring to diagrams, so:
LTP: Long Term Plan - the base diagrams that include the services which form the Working Time Table, usually valid for a set period of time e.g 3-4 months
STP: Short Term Plan - amendments to the LTP, usually issued on a shorter time scale i.e weekly, could be due to extra services, engineering possessions, change of traction etc etc
VSTP: Very Short Term Plan - Moves planned on the day or within a very short notice period, e.g moving a failed unit/loco back to a maintenance depot.
LTP/STP will come from the Train Planning Unit, VSTP will more than likely be submitted by the relevant Control.