Rules and "machinery"?

I keep finding examples in the manual that refer to things further along in the manual. So I finally decided to jump into chapter 19. Right at the start it says: “When we open the casing and look inside the machinery of Inform, what we see are rules and rulebooks. We seldom need to know how this machinery works”

My understanding is that rules are the basis for just about everything, from every turn rules to instead rules to de-listing rules and so on. In fact, many examples well before the Rulebooks chapter say I need to understand some stuff about rules to even understand the example. So I fear I’m not getting some distinction here. What’s the “machinery” that we seldom need to understand?

I think “machinery” here refers specifically to the rules and rulebooks in the Standard Library. If you look at the IDE’s rules index, for example the turn sequence rulebook lists these rules:

While the names give me a general idea of what any given rule might do, I have no idea how they work internally. I would only go through the Standard Rules if I had to radically change how the system works.

In fact the full quote supports this:

My reading is that while it’s important to know how rules work in general, it’s not that important to fully understand every detail of the rulebooks in the Standard Rules, unless you need to completely replace a basic feature of the world model.

That makes sense; thanks. Your last sentence in fact should probably replace the one in the manual.

To add, I believe that’s referring to the mechanism of the rule books, not their contents. It’s thus easy to add an Instead rule, but harder (although possible) to replace the Instead rulebook altogether.