For advtrains, a signal aspect can contain the following information:
The main signal aspect,
Whether the train may proceed as shunt move,
Whether a train in shunt mode may proceed under the main aspect, and
The main signal aspect of the next signal (“distant signal”, not used).
The main and distant signal aspect can show one of the following:
Do not proceed (“danger”)
Proceed with the given speed limit
Proceed while retaining the current speed limit
Proceed without any speed limit
Trains in shunt mode have the speed restriction of 6.