NEW YORK -- The NFL is anticipating only a handful of ejections this season as part of a new rule that prohibits players from lowering their helmets to initiate contact -- one of the primary takeaways Tuesday from the first day of a player safety summit at league headquarters.

A review of 40,000 plays from recent seasons revealed less than five instances of what would be considered a flagrant, and thus ejection-worthy, violation, according to NFL executive vice president Troy Vincent. One was a hit by Chicago Bears linebacker Danny Trevathan on Green Bay Packers receiver Davante Adams last season in Week 4, for which Trevathan was later suspended.

Penalty flags for the expanded rule -- which replaced a previous prohibition on using the crown of the helmet to initiate contact -- are expected to increase in 2018. But during the meeting, as well as in side conversations, Vincent and other league officials sought to downplay the possibility of the kind of mass ejections that characterize the NCAA targeting rule.

"We want officials to enforce the rule," Vincent said. "I don't want to say it's going to be two, three, five [penalties per game] or whatever. If they see it, call it. ...But there were four plays that we saw today that would rise to the level of ejection based on the new rule. That's it."

League owners hastily approved the rule in March before it was fully fleshed out. As written, it calls for a 15-yard penalty and a potential ejection on any player who "lowers his head to initiate and make contact with his helmet against an opponent." It will apply whether the player hits an opponent's helmet or any other part of his body, but it is "not to include bracing for contact," according to the verbiage.

That caveat generated animated debate among the more than 50 owners, coaches, executives, officials and former players in the room. A handful of reporters sat in on portions of the meeting, as the group watched video of various plays to learn what the league considers legal and illegal plays.

Representatives of the competition committee pointed out that officials will draw a distinction between simply lowering helmets -- which happens on every play -- and the intentional act of lowering it to initiate contact with the opponent.

"I'm here because I wanted to get clarity on this," Los Angeles Chargers coach Anthony Lynn said afterward. "I can watch this stuff on video, and I asked six times: Can you rewind that? I don't have that option on the field. I just want to see how they're going to officiate it when its full speed on the field."

Lynn said he finished the day "clearer" than when he began. But group consensus on some plays was difficult to reach. Most notable was a run last season by New England Patriots tailback Dion Lewis. On the play, both Lewis and Atlanta Falcons safety Ricardo Allen lowered their heads into each other. Should Lewis have been penalized? Allen? Neither? Members of the competition committee and officiating department disagreed during the discussion.

Coaches in the room included Lynn, Dan Quinn (Falcons), Mike Tomlin (Pittsburgh Steelers), Todd Bowles (New York Jets), Mike Vrabel (Tennessee Titans) and Matt Patricia (Detroit Lions). Several of them voiced concern about whether running backs will be held to the same standard, and whether they would need to be taught new techniques on the fly. The same is true for, say, pulling guards and running backs who are blocking blitzers.

Quinn made a suggestion that was quickly adopted: Head coaches throughout the league will collaborate on a position-specific teaching video for teams to study during training camp. The coaches would provide the voice-overs to distinguish from standard NFL videos.

"I'm close to 90 percent clear on this," Quinn said. "The thing that's keeping you up at night is the way to get it taught at each position. [With the coach videos], that way we're all teaching under the same guidelines. This isn't a team issue. It's an issue of how we're trying to make the game better. It's time for all of us to share the right examples. It has nothing to do with Team X's technique being better than Team Y's. It's more like getting all 32 teams to be on the same page and talk the same way."

League officials will use Tuesday's discussion to finalize a set of standards for ejection. Owners also must approve the use of replay to review ejections, likely during the May 21-23 spring meetings. Most people in the room Tuesday agreed that replay should be a mandatory safety net for officials tasked with ejecting players who flagrantly lower their helmets to initiate contact.

"I think we're going to have to have replay for ejections," Lynn said.

The second day of this two-day summit will focus on the future of the kickoff. Vincent said Tuesday that the league is not planning to eliminate the kickoff for 2018, but instead hopes to make heavy modifications to make it safer. Wednesday's meeting will feature a brainstorming session as well as an attempt to build a consensus for writing a new rule, one that could also be approved by owners in May.