Explanation of the signal images caution signal and replacement signal:

The free aspect of the main signal is indicated by a line running diagonally upwards to the right. A signal imitator can also indicate a replacement signal on the corresponding main signal by means of a white flashing light in the bottom right corner.

Explanation of the signal imitator with replacement signal:

The free term on the main signal is indicated with a line running diagonally upwards to the right. A signal imitator can also indicate a replacement signal on the associated main signal with a white flashing light in the bottom right corner.