Question about Optimization Levels

[p-bakker]

Rhino supports optimization level -1 through 9.

Am trying to check old documentation for porting over to our new documentation and trying to find what the different optimization levels do, but I cannot find any difference between optLevel 1 through 9: nowhere in the codebase can I find any code that acts on any of the specific values 1 through 9. The only thing I can find are if statements that check whether the optLevel > 0

Am I missing something somewhere?

[C-Masuda]

I've never seen any explained difference other than what's available in the old doc via wayback machine.
Edit: which is exactly what you've got on your placeholder repo.