Numbers question (jersey)

I know by rule OL must be between 50-79.

I think QB must be between 1-19.

DL have to be between 90-99????



I used to think WR and TE had to be in the 80’s.....but that’s not the case. At least for WR, not sure about TE.

AK seems like the only 41 Rb in NFL history, though I can’t confirm that.

Seems RB have always been between 20-39.......with fullbacks getting the obligatory “42”.

K/P always single digits.

Are these by rule, or just traditions over time?

LBs seem to have exclusive rights to 50’s.

Darren Sproles was 43.