Dan Graziano breaks down the NFL rule adjustments made this offseason, including players wearing hoodies and assistant coaches on the playing field during games. (1:44)

NFL players no longer can wear exposed "hoodies" over their shoulder pads, and assistant coaches are now expressly prohibited from entering the field of play, following a series of adjustments that will appear in the 2016 edition of the NFL rulebook. Both were in response to specific issues that arose during the 2015 season.

The final version of the book has not been published, but a league source confirmed the changes to ESPN's Ed Werder. Former NFL vice president of officiating Mike Pereira, now a Fox Sports analyst, first revealed the changes on Twitter.

The "hoodie" rule was deemed necessary after receiver James Jones debuted the style last season while playing for the Green Bay Packers. The hood at times blocked Jones' nameplate on his back. Because it is a uniform policy adjustment, it did not require a vote of owners.

It's not all good for James Jones' hood as the NFL has updated its rule book to prohibit players from wearing hooded sweatshirts during games. Tommy Gilligan/USA TODAY Sports

Meanwhile, the NFL moved to codify what had been an implied rule for some time. Head coaches are the only coaches allowed on the field during games, and it is permissible for no reason other than to check on injured players. This adjustment was aimed at Pittsburgh Steelers outside linebackers coach Joey Porter, who wandered onto the field during a wild-card playoff game in January against the Cincinnati Bengals.

As medical officials checked on the condition of Steelers receiver Antonio Brown, who would be diagnosed with a concussion, Porter got into a shouting match with multiple Bengals players. Ultimately, cornerback Adam Jones was penalized for his role in the exchange, putting the Steelers in position for a game-winning field goal.

Finally, the NFL addressed another incident from last season for which the rulebook offered no direct guidance. If a coin does not flip during the pregame (or pre-overtime) toss, the referee is now directed to retoss with the captain's original call still applying.

Referee Clete Blakeman followed that procedure during a divisional playoff game between the Packers and Arizona Cardinals prior to overtime, but at the time the NFL said he used his own judgment and confirmed it had no rule to use for such situations.