Comment: Helmet rule is there for protection of players - every hurler is well aware of the consequences
You may as well familiarise yourself with it now because it could run and run in the build-up to next month's All-Ireland hurling final between Galway and Waterford.
To save you the leg work, it's rule 5.19 in part two of the 2017 version of the GAA's Official Guide.
It's there in black and white on page 52 and reads: "To behave in any way which is dangerous to an opponent, including to deliberately pull on or take hold of a face guard or any other part of an opponent's helmet."
That's the definition out of the way. And now the debate will rage as to what, if any, sanction Austin Gleeson should face after his clash with Luke Meade.
You'll hear all the arguments that will range from 'the rule couldn't be any clearer' to 'the All-Ireland final would be a lesser place without one of the game's most exciting talents'.
There is merit in both viewpoints but the truth is somewhere in between, and now it's up to the GAA disciplinary chiefs to navigate their way through it all and find the right outcome. Considering the circumstances, it's a most unenviable task.
Interfering with a helmet became a straight red-card offence ahead of the 2014 campaign and until this season, it has generally been a non-issue.
Podge Collins was the first high-profile player to be hit with a ban under the rule. He tugged David Redmond's face-guard when his Clare side met Wexford in a qualifier that summer and he was sent off on the spot.
The pair squared off and Collins yanked the guard open in view of the officials. It looked exactly like the kind of offence the rule-makers had in mind when they decided that the risk associated with helmet interference, and the type of injury that could come from it, merited a straight red card.
It had a relatively low-profile start to life in the Official Guide and other than that Collins incident, the rule has been largely dormant in the consciousness of GAA people.
It is only really this summer that the rule has come into focus. And like many things in the GAA, it has polarised opinion.
Speaking earlier this year, Kilkenny legend JJ Delaney wasn't pleased when Stephen Bennett of Waterford picked up a ban for pulling off Damien Cahalane's face-guard during their Munster semi-final back in June.
"It came in a few years ago and it just came in, I don't know what incident happened to be honest with you that they made this rule come in," Delaney said.
"It's something that I didn't think was actually too bad within the game because I can't think of too many occasions where it did happen.
"Fair enough if a lad came in on a row and he pulled the face guard off and they box away, fair enough that's a red card no problem at all.
"I don't think it's a red card, to be honest with you. You could give a lad a dig and break his ribs and no issue he might get a yellow. If you touch a lad's face guard it's a red card.
"Maybe it looks worse than maybe it actually is to be fair, if someone pulls your face guard you wouldn't get too many injuries. Maybe in and around your eyes you might get hurt that way."
Delaney's point is that the rule probably wasn't that necessary in the first place and now that it is here, it's too rigidly enforced. The punishment, he reckoned, didn't always fit the crime.
But then, a lot of the changes that come into the GAA are met with some form of resistance.
When helmets were made compulsory for adult hurlers ahead of the 2010 season it was met with derision from some corners.
Speaking at the All-Stars tour just months before helmets became mandatory, then Waterford star Eoin Kelly insisted the GAA were treating players "like kids".
He wasn't alone in his unhappiness but research has since shown that the number of head injuries in the game has reduced dramatically.
A 2013 study in Cork University Hospital showed that 7pc of injuries to hurling and camogie players were to the head, well down on the 28pc recorded in a similar 1984 study and 20pc in 1993.
There's no evidence to suggest that this sanction around face guard and helmet interference has reduced or prevented injury but everyone knows the rule is there and why it is there. Player safety must always be paramount.
Waterford and Gleeson could hardly have been more aware of the rule in last Sunday's All-Ireland semi-final given the build-up they had with the Tadhg de Búrca saga, along with Bennett's ban from earlier in the summer.
When he put his hand on Meade's helmet, Gleeson must have known it had the potential to open a can of worms for himself, Waterford and the GAA, who now face the prospect of the most novel All-Ireland hurling final in years without arguably its most exciting star.
The power-brokers will know that Hamlet doesn't work without its prince.
The rule has been an almost constant undercurrent in this hurling summer. To underline just how much the controversial rule has dominated the discourse, one bookmaking firm was quick out of the blocks yesterday morning to announce that it was offering odds on whether Gleeson would play in the All-Ireland final.
De Búrca's suspension stood and he had to sit out the game in Croke Park last weekend. Adrian Tuohy wasn't hit with any proposed suspension after he made contact with the helmet of Patrick 'Bonner' Maher as Galway saw off Tipperary the previous Sunday.
Waterford people might point out that while it might be relatively easy to say Gleeson intended to remove Meade's helmet, they can ask whether what Gleeson did could be deemed as dangerous, according to the rule.
No matter what happens it is important to note that the rule was brought in for no other reason than to protect players and as long as it serves that purpose, it deserves to be there.
In the meantime, we're looking at a hell of a mess where the GAA will be damned if they do ban Gleeson and damned if they don't.
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