[A]	Auto button provided for route indicated.
[P]	Preferred route: where more than one route is provided between the same two signals. If free, the preferred route will be set. If not free, the alternative route will be set, if this is free.
[Q]	Main route which is approach released from Red unless exit signal shows a proceed aspect
[R]	Main route which is approach released from Red
[S]	Held at Red until route set from signal 826
[Y]	Main route which is approach released from Yellow
*	Yellow aspect only when cleared
