What are the US codes?
 

NFL
AFL
NCAA
NFHS


Any others?

In terms of major codes, I would include that of the USFA (or a similar named organiz'n, I forgot which) whose rules are used as is by some minor adult men's leagues, as a model by some others, and with modifications by one women's league last I heard. However, since there's one large women's league now, perhaps you could include theirs if it's not that one. Pop Warner last I heard had a single rules set organiz'n-wide, as opposed to AYF and others that allow local leagues to adopf their own rules, so you might consider theirs too. There's probably one prominent organiz'n for touch or flag football, you could include theirs. NAGWS used to have their own flag football rules, I don't think they do now, but I could be wrong. There's also IFL, the indoor game that doesn't use AFL's proprietary features.

Fed has their own rule variations for 6s, 8s, and 9s now, so I think you count that all as part of NFHS.

If you want to count the code of every distinctive type of football, then I guess whatever rules Town Beef (no pads tackle) uses. There's also women's 6s.

Of course there would be a host of minor rules codes used by some private high school leagues (if they still do that sort of thing), the other women's league(s), men's leagues, and most especially youth football. Youth football leagues can have extremely idiosyncratic rules variations that frequently are conveyed only by word of mouth -- and I don't mean just what their officials choose to enforce, nor eligibility restrictions, I mean actual playing rules variants affecting such things as formations, motion, timing, and scoring.

AIUI, the fall rookie pro league that started a couple years ago uses NCAA rules, but I wouldn't be surprised if they have their own variations by now.

Square toe kicking shoe?
 

Are these still legal in high school?