When a 40 minute half of rugby can last 50

There are a lot of numbers involved in a game of rugby and some of the important ones relate to time.

A rugby game normally comprises two 40 minute halves – less on a sliding scale for younger players.

Of course, a half can last longer if the ball is in play when the forty minutes is up, especially if the play ends in a penalty kick, which can then lead to subsequent plays before the ball finally becomes dead.

If my memory serves me correctly, one recent Six Nations match being refereed by Englishman Wayne Barnes lasted almost 50 minutes, with a lot of the extra time being spent on scrum resets and scrum penalties.

One variation on the two halves is that players can be allowed a one-minute water break midway through a half in hot and humid conditions, as happened in a Super game in Sydney earlier in the year, but I can't see that happening here any time soon.

The time taken for halftime can vary, as the rules state it can last "up to 15 minutes".

Higher level matches, such as internationals and Super Rugby, use the longer time for players to recover from the rigours of the first half and to prepare for the second, as well as to cater for the sponsors' advertising.

Local rugby tends to stick to the traditional five minutes, although I once played in the snow in Central Otago at a wild and exposed place called Becks in the Maniototo Basin, where it was so cold we just changed ends and started playing the second half straight away.

It was not the sort of day you forget in a hurry.

If a player is injured, a referee may stop the game for up to one minute so the injured player can be treated on the field.

If the treatment is going to last longer, the player should be removed from the field so that play can continue.

This particular clause can cause some friction between players and the referee if one team (or the referee) thinks the player's team is gaining an advantage from the stoppage, especially if it occurs several times in a half.

For some reason prop forwards are often involved.

However, if the injury is serious and removing the player would further aggravate his condition, the one minute can be extended until the player is treated by specialist staff before being moved.

A player yellow-carded is sinbinned for ten minutes playing time, where the time taken for halftime does not count.

So, a player sinbinned with three minutes to go until halftime will have another seven minutes to sit out at the start of the second half.

The time in the sinbin actually starts when the match resumes, as the offending player either reaches the chair in big time rugby, or more likely his opponents' dead ball line, where he has to remain for the ten minutes.

Some "unsmart" players amble back towards the dead ball line, thinking they are using up some of the ten minutes, but not so as time starts when they reach that line.

Two other time-outs involve actual, or real time, when the clocks are counting.

A player leaving the field to have a bleeding injury attended to has 15 minutes of actual time before he must return to the field or be considered as "permanently replaced" and thus unable to return to the field for any reason.

If a player leaves the field with blood within 15 minutes of halftime starting then they must resume playing at the start of the second half or be considered as permanently replaced.

In higher level matches where a team or match doctor is in attendance players who receive a knock to the head may leave the field to have a Head Injury Assessment (HIA).

Such players undergo a standardised assessment and have 10 minutes actual time to return to the field before being permanently replaced.

So, if such a player leaves the field within ten minutes of halftime then he needs to return to the field for the start of the second half in order to keep playing.

Team management usually make these decisions.

In local rugby, if a referee recognises a player has had a knock to the head and may have been concussed, then he has the power to remove that player from the game permanently.

For Premier and Senior matches he may issue a "Blue Card" to the player who must then leave the field. Player safety is paramount here.

This is a referee responsibility and over-rides any attempt by the player or team management to keep that player on the field, even if a Blue Card is not issued.

At a penalty kick at goal, the kicker has 60 seconds from the time of indicating a kick at goal to taking it, even if the ball falls over and has to be replaced on the kicking tee.

Otherwise, a scrum is called at the place, with the kicking team putting the ball in.

After a try is scored, a team has 90 seconds from that time to take the conversion kick, even if the ball rolls over, otherwise the kick is disallowed.

Lastly, if a player claims a "mark!" inside the 22m line, a free kick is awarded and must be taken within 60 seconds.

This includes if the player taking the mark is injured – if he is unable to take the kick then a scrum is awarded to the kicking team at the mark.

A referee has to keep track of all these different time allowances without becoming flustered, not an easy task at times.