Haven't found anything on this. Could anyone elaborate?

Wow, thanks a ton, Acmlm!

Can't say I understood this part:

• Odds of spawning 1/2/3 enemy groups
• 8 possible enemy groups, with enemy id, odds of being selected, odds of spawning 1/2/3/4/5/6/7 enemies

I don't see anything describing that @ https://pastebin.com/kwhc44ZE Could you, please, elaborate/explain?

More specifically:

1. How does the game determine how many enemy groups to spawn (1/2/3)?
2. Why did you say "8 possible enemy groups" if it's "1/2/3"? What am I missing here?
3. Where can I find the data on possible enemy groups, enemies that can go in, odds of being selected, odds of spawning 1-7 enemies in a given group?

Sorry if that sounds too noob-ish, after all I am a newbie.

If there's a guide/video/article whatever explaining that stuff, I'd be so grateful if you could point me towards it.

Can anyone elaborate on enemy zone levels? The table from pastebin doesn't 100% correspond to the data found in ROM (EU, Steam). What are the numbers on the left? How do I deduce what is 1b or 3f in here? (Do I just assume each rom is a letter? i.e. a, b, c, ect) Does "2f-3b" mean "through"? i.e. "2f, 3a, and 3b"? 1: 3 4 6 2: 7 8 9 10 11 12 3: 13 13 14 15 4: 16 17 18 19 20 5: 21 22 23 24 6: 25 26 27 28 7: 29 30 31 32 33 8: 34 35 36 37 9: 38 40 42 43 44 45