Fashion and style are two very different things. The first is fleeting, the second more permanent; an inherent sense what is correct, what is just so. Rugby is no different, and finally a fashionable focus might have turned to one of the more dangerous tackling techniques.

The Rugby World Cup saw some fashionable crimes. The neck roll became part of the furniture over those couple of months then seemed to take a well-earned winter break.

After its convalescence the neck roll is being picked up again, but it’s still causing confusion. Let’s clear this up: it’s not an automatic card, rather the offending player “runs the risk” of a card or sending off if they deliberately grab or choke the head or neck. Penalty? Yes. Yet consistency is still a problem.

In the same game in Twickenham last weekend a neck grab by Owen Farrell was correctly penalised while Joe Marler's bit of work on Conor Murray as the Irish man dotted down in Twickenham was not. Tryscoring can be like that, with a reward for many a tryscorer being a set of knees in the back for their troubles. A penalty on the half way line after the conversion and a possible yellow card would clear things up nicely.

But when officials are looking closely at the act of try scoring, their focus is often understandably on tryline, touchline, or ball.

Focus is a double-edged gift. Consider a group of people passing around two basketballs. Three wear white, three black. It's a famous piece of film, an experiment designed by Daniel Simons and Christopher Chabris exploring the concept of Inattentional Blindness. Your task as observer is simple: count how many times the players wearing white pass the basketball. Twenty-three seconds into the video a seventh figure enters the scene. It is a gorilla, visible for nine seconds of the 37 second long sequence. Such is the brain's focus on the task at hand, Simons and Chabris found that half their subjects did not remember seeing a gorilla.

Focus can be good when it comes to highlighting and dissuading rugby crimes.

Apart from the neck roll, in recent times focus has descended on the no-arms clearout, sometimes dressed up as barging into a ruck. This is excellent news. There is a powerful disciplinary focus on hands or fingers near an opponent’s eyes with bans to match, seemingly less so when it’s a flailing boot involved instead.

The crooked feed's time in the sun was a brief but glorious surge in decisions at the start of the 2013/14 season, including a yellow card issued by Greg Garner at the RDS to Castres scrumhalf Julien Thomas who wasn't even the starting halfback who had issued the first two squint feeds. The focus had dimmed in France; in the Top 14 it had taken just five weeks for the directive on crooked feeds to be ignored to the extent that the LNR's Central Commission of Referees said that they had made the referees aware of the directive again.

Crooked feeds

Forget the misconception that the ball must go straight down the centre; the ball can be fed in line with the attacking team’s shoulders so long as the ball travels credibly square to the scrum itself.

While to many eyes the credibly straight feed is again a rare sight, according to Opta's data in the 499 scrums in Six Nations matches since 2014 referees have awarded just four crooked feeds.

The next focus might well be the chop tackle, with Dan Lydiate its poster boy.

The Welsh blindside does one thing particularly well, cutting people off at the shoelaces allowing colleagues to bail in and poach. It’s his trademark move, but Mr Lydiate is now running into problems. The Welsh man was penalised against France for a no-arms chop tackle.

The weekend before? A yellow card in a club game for a similar offence. This might be coincidence, but this column hopes it is not.

Legitimate tackle

When many focus on the rise of the choke tackle high up the chest it might seem harsh to give out about somebody going low. But it must still be a legitimate tackle. An important part of the sequence is an attempt to grasp, and that’s not just an arm stuck out for optics.

When that bony part of the shoulder arrives between ankle and knee without a grasp an opponent’s lower leg could be torpedoed.

This highlighting of a dangerous flaw in tackle technique might be another fleeting officiating fashion.

For the benefit of those potentially on the losing end of a low Lydiate shoulder-chop it’s a change that should become a permanent style.