Actually, you can’t specify macros anywhere. Unlike TeX, it’s a real honest-to-goodness programming language with functions and types and modules (yes! It has namespaces!) instead of just macros on macros on macros.

It’s not perfect, they definitely made some interesting choices here and there, but this makes it ~80% less painful than TeX when you’re doing anything other than happy-path undergrad-lab-report writing.

(To be clear, I know you know this! I’m writing this for the benefit of all sentient beings :))