Yep, the goal here is 1 of N shared access to the location with N being however many of the vertical blocks you have.

The bit to the left with the chain on it has a C cut into it if you look down from above. Remove any one lock and you can slide the other verticals to the right enough to pull the chain out towards the photographer.

I realized after I left I should have taken more photos to show the clever mechanical trickery so that the upside down bars are full time locked when upside down but if you pull any other lock bar you can flip it and add a lock to do an N=N+1.

If you are a paranoid like me it is a moments head scratching how to ensure you can't be locked in by someone else while working. You have to take the vertical bar that you removed with you to go do your work.