[CompSci87]

I don't remember where I saw this but I think the numbers in the 50's, 60's and 70's are not to be used for positions that normally touch the ball on offense, i.e. backfield and receivers.  I believe it is supposed to help the officials detect when an ineligible receiver is downfield.

Yes, eligible receivers (backs and ends) cannot wear numbers between 50 and 79. Actually you can line up as a back or end wearing such a number, but you are still ineligible -- unlike the NFL where you can report to the ref as eligible before each play.

Also I think if you are wearing an eligible number on offense you must line up as a back or end, but I'm not as sure about that.

Those are the only college rules about what numbers must go with what positions. The NFL has a lot more.

[CompSci87]

I don't remember where I saw this but I think the numbers in the 50's, 60's and 70's are not to be used for positions that normally touch the ball on offense, i.e. backfield and receivers.  I believe it is supposed to help the officials detect when an ineligible receiver is downfield.

Yes, eligible receivers (backs and ends) cannot wear numbers between 50 and 79. Actually you can line up as a back or end wearing such a number, but you are still ineligible -- unlike the NFL where you can report to the ref as eligible before each play.

Also I think if you are wearing an eligible number on offense you must line up as a back or end, but I'm not as sure about that.

Those are the only college rules about what numbers must go with what positions. The NFL has a lot more.