60–79: Defensive linemen and offensive linemen other than centers
80–89: Wide receivers and tight ends
Numbers 0, 00, and 90–99 are no longer allowed to be issued, even though these numbers were rarely issued anyways. Numbers 90–99 would be allowed again in 1984 for defensive linemen and linebackers in addition to the above mentioned numbers.
Defensive players cannot jump or stand on a teammate while trying to block a kick.
The clock is to start at the snap following a change of possession. Previously, the clock would start on a change of possession when the ball was spotted ready for play by the referee.
If there is a foul by the offensive team, and it is followed by a change of possession, the period can be extended by one play by the other team.
If the receiving team commits a foul after the ball is kicked, possession will be presumed to have changed; the receiving team keeps the ball.
Starting in 1970, and until 2002, there were three divisions (Eastern, Central and Western) in each conference. The winners of each division, and a fourth "wild card" team based on the best non-division winner, qualified for the playoffs. The tiebreaker rules were changed to start with head-to-head competition, followed by division records, common opponents records, and conference play.