I must confess I'm not entirely sure I understand how they work myself so the show at Dinas next month is going to be a steep learning curve for the entire operating team.
From what I can gather the red LEDs indicate the isolated sections for loco holding as stabling.
(What I don't know yet is whether light on means the section is live or dead - I can see collisions!)
And the green ones show which road / route has been selected.
I'm presuming that the rotary switch relates to the maze of point work at the yard throats and the ones at the run round end are linked to the vertical switches controlling the direction of the points connected to the head shunts.
What's truly remarkable about all this, if you ask me, is that it's entirely analogue and there's not a DCC chip anywhere to be seen.
Which is just how it should be.