In Fig 2, train 7752 is scheduled to depart on the Down line. The signalman has set up the route and his action is confirmed by the white track circuits along the route showing it is selected, available and locked. The icon of signal C23 is showing a green aspect to indicate that that the signal has cleared.
Fig 2 - Route Selection
Signals C23/C25 are approach locked. This means that routes over which they "read" cannot be set up unless track circuit 107 has been occupied for, in this example, at least 30 seconds. This ensures that a train occupying this track circuit has come to a stop and will not run onto the points while they are being changed.
Although the route is cleared, the train description will not normally be shown in the black box over the block ahead until the train occupies the block. Signal A201 is automatic and will always show a green aspect if the line ahead is clear for normal speed.