Teams will need to nominate a ruckman at each contest to allow umpires to adjudicate the new 'third man up' rule introduced this season.

New AFL umpires boss Peter Schwab said getting a player to raise their hand might be the simplest way for each ruckman to indicate his intention to contest the hit-out, but the practicalities were still being resolved.

"We will ask them to nominate," Schwab said.

"[A] show of hand might be the easiest way and if they don't then the umpires are going to have to quickly say [you and you] like the old school yard."

He conceded there might be some teething problems with issues such as two players from the same team nominating as the ruckman at the same contest, but ways to handle those matters would be clarified over time. 

"We expect the clubs will be very helpful with us on that and we shouldn't have too many problems," Schwab said. 

Banning the third man up at ruck contests was the most contentious rule introduced during the off-season, with senior players voicing their disapproval and some coaches questioning whether change was necessary. 

However Schwab said the desire to protect the role of the ruckman and evidence that clearances from congestion weren't improving when a third man became involved in the contest was enough for the AFL Commission to approve the change. 

In 2017, a player will not be penalised for high contact if the tackle is reasonable and his opponent with the ball is deemed to have initiated the high contact.

Umpires will also interpret the deliberate rushed behinds rule more strictly.

Players will be deemed to have deliberately rushed a behind if they have clear possession and the chance to dispose of it, or they are outside the goal square when rushing the behind. 

"We'll work on fact," Schwab said.

"We know there is perceived pressure with players but the umpire will look at it and say 'well I think the player had a lot of time to do something and elected to take it over'." 

If a player breaches the rule during the JLT Community Series, a ball-up will occur just outside the goal square. Previously, a deliberate rushed behind led to a free kick to the opposition directly in front of goal. 

Schwab said interpreting high contact was more subjective but the umpires knew the intent of the rule.

"If the player's legitimate attempt to tackle appears to be correct and the high contact is caused by the player ducking into the tackle, dropping his knees or trying to shrug it off then it will be a play-on call," he said.