MLS officials will focus on four new points of emphasis in the 2017 season, Professional Referee Organization general manager Peter Walton said in a conference call with reporters Friday.

Walton said that MLS referees have been instructed to pay closer attention to holding and pushing in the penalty area on set pieces, acts of visual dissent, deliberate delaying of restarts, and persistent infringement.

He also outlined the changes to the Laws of the Game that will take effect in MLS for the first time this season. The International Football Association Board (IFAB), the body that decides on changes to the Laws of the Game, changed several of the sport’s rules last May.

The major changes include no longer automatically giving red cards for denial of an obvious goal-scoring opportunity in the penalty area, kickoffs now being permitted to be played in any direction, and players who were injured by a yellow or red card foul now being able to briefly receive treatment on the field without having to come off.

The amended rules were in effect at international tournaments last summer and are currently in place in European leagues that began their seasons in August, but were not put into effect in MLS in 2016, as the season had already begun by the time the changes were ratified.

A full rundown of the IFAB rule changes can be found here. Details on the new points of emphasis are below:

Holding and pushing in the penalty area

Walton said that MLS referees will be paying closer attention to holding and pushing in the penalty area on set pieces, and that they’ve been instructed to detect and punish offenders that are “clearly impeding the opponent” without making an effort at playing the ball.

“Bracketing or jockeying players is all part of the game and is an accepted part of the game, as far as I’m concerned," Walton said. "But the overt pulling and pushing that happens where the defender or the attacker just doesn’t have their eyes on the ball and is clearly impeding the opponent, those are the sorts of ones that we want detected and indeed punished."

Acts of visual dissent

MLS officials will be cracking down on what Walton called “acts of visual dissent” in 2017. According to Walton, referees “won’t condone” players or coaches who react to calls with “arms thrown in the air” or by racing “after an official to berate them.” Dissent can be punished by a yellow card caution.

Delayed restarts

Walton said that MLS officials will have less patience this year for players who kick a ball away or stand over a free kick to make sure that it can’t be taken quickly. He said that he’ll look for officials to be aware of teams or players who deliberately try to delay an opponent on a restart, and to caution blatant offenders with a yellow card.

“A lot of teams in Major League Soccer now play good pass and movement games, possession games and as part of that tactic they’d like to see the ball being put back into play quickly. And that’s something again that opponents are picking up on that and denying them that opportunity,” he said. “What’s required from our referees is that they must be aware of when players are trying to deliberately delay restarting the game and punish accordingly.”

Persistent infringement

The fourth and final point of emphasis for MLS officials in 2017 is on persistent infringement. Walton wants referees to be cognizant of the “small, petty fouls that don’t rise to a yellow card nature in isolation, but break the rhythm of the game and upset opponents.” He said that all four officials will be “charged to detect areas of persistent infringement,” but wouldn’t put a number of how many fouls would merit a yellow card, instead relying on officials to manage their individual games appropriately.