Where are my circ rules in the database?

I often find it helpful to look at circ rules via a report, but have a heck of a time remembering which tables that data goes into. After a lot of learning, forgetting, and re-learning, I finally broke down and made some notes. Here they are, to spare you my frustration. These are correct as of 19.05 and should remain so in 19.11. When 20.05 rolls around some of this will change.

UPDATE: You can find a comparable post for 20.05 and later here.