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Each effort to inject more clarity into the new helmet rule invites more potential ambiguity to its eventual application.

The latest new item of evidence regarding the broad, possibly revolutionary rule comes from an apparent 11th-hour addition to the new language of the specific provision of the unnecessary roughness rule that relates to helmet use. Of course, that’s not where the rule prohibiting the lowering of the helmet to initiate contact appears; the unnecessary roughness rule generally bans ramming, spearing, or butting with any portion of the helmet, without a requirement that the helmet be lowered or that contact be initiated.

The new language comes in the form of a “note” that apparently was added at some point after the league (incorrectly) cited to Dom Cosentino of Deadspin.com the unnecessary roughness rule as the codification of the new helmet rule. Here’s the full text of the new note: “This provision does not prohibit incidental contact by the mask or the helmet in the course of a conventional tackle or block on an opponent.”

So the new formulation of this specific aspect of the unnecessary roughness rule has removed the prior requirement that the butting, spearing, or ramming be violent or unnecessary, but it has added a caveat that allows incidental helmet contact arising from “conventional” tackling or blocking. Which means that the unnecessary roughness rule for 2018 encompasses non-incidental and/or unconventional use of the helmet, without the lowering of the helmet or initiating contact with it — and without regard to whether the use of the helmet was violent or unnecessary.

This leaves the league’s game officials with a jumbled stew of phrases and clauses that they will try to apply in real time, with consistency, accuracy, and reliability. Amid the unprecedented departure of nearly 25 percent of the league’s referees. With ever-enhancing attention and scrutiny, thanks to the spread of legalized gambling.

In more than three months since the new helmet rule first made its appearance, as an unexpected and unpublished proposal submitted to owners without anyone outside the league knowing about it, multiple coaches and league officials have tried to downplay its eventual breadth and impact. With each additional adjustment to the rulebook, however, it’s become clear that this is indeed a big deal.

And that it has the potential to become an even bigger mess.