As part of our Six Nations coverage, we gave you the chance to quiz two top Welsh referees about the laws of the game.
Hugh Watkins answers your last round of questions from a thrilling Six Nations tournament.
When you ask the television match official to clarify a particular incident, does the referee always accept their decision or is the final word with the referee?
Steve Watson, Warrington
We can only consult the TMO for anything that happens in the in-goal area.
Therefore, if you ask for a ruling on the grounding of the ball, the TMO will watch the screens and come to a decision.
Sometimes the evidence is not clear and the TMO will hand it back to the referee to make the final decision. These are few and far between - thank heavens!
But in answer to your question, the referee is the sole judge.
In Wales' game against France, Shane Williams was not awarded a try because the French defender was deemed to have touched the ball down.
Shane Williams was denied a try by Yannick Nyanga's stomach
The replays clearly showed the only downward pressure applied was with his stomach. Does this constitute grounding the ball?
If so, then can you also score tries without touching the ball down with your arms, or does this rule only apply to the defending team?
There are many ways to ground the ball; by holding it in your hands or arms, by pressing down on it with hand, hands, arm, arms or the front of the player's body from waist to neck inclusive.
And this applies to all players. So yes, by using the stomach the ball is legally grounded.
Is it true that if part of the ball makes contact with the touchline it is out and play should restart with a line-out?
Adrian Williams, Scotland
Yes, if the ball crosses the touchline then a line-out is called, unless it is from a penalty.
On a quick line-out, does the throw have to be straight or can it be thrown backwards?
Any player can throw the ball in at a line-out
What other points does a player need to observe taking a quick line-out?
Good question, Adam. Here are the laws regarding quick throw-ins:
Must use the same ball
Has not touched a spectator or any other person
Must be taken anywhere from where the ball crossed the touchline and the player's own goal-line
Must travel five metres and be straight
On the last law, we need to apply common sense. If the throw is a little crooked, then generally we will allow play to continue.
Can a player call a mark from their own 22m directly from a penalty which has not found touch?
Billy Mills, Orpington
Yes, a player can call a mark anywhere within his 22 and the goal-line from a penalty or from a kick in open play which has not touched the ground.
Does the hooker have to throw in at the line-out? If no, can any other player do it?
Paul McNerlin, Belfast
Any player can throw the ball into a line-out.
What is the gainline?
The gainline represents an imaginary line at the place where there is a scrum, ruck, maul or line-out.
The side who are in possession of the ball will attempt to make ground past the mark where the set-piece took place.
Can you explain a little behind the history of the 22m line? Why 22 and not 25 or 20?
I'm not that old, so unfortunately I can't tell you the history of it!
I know it was called the 25-yard line before we moved into the metric system.
Sorry, I can't help you on that.
(Dr John Berridge writes in to tell us the 22m is the nearest metric equivelant to the old 25-yard line)
How exactly can you score a try by putting it against the post?
Does it have to be against the post and ground (the side in front of the tryline) and does it only count if there were bodies in the way around the post?
Or can you deliberately aim for the base of the post if you think it is going to be an easier score?
You can score a try against the base of the post.
The post protectors also count as a try if the ball is grounded at the base of that post.
If the ball is grounded on the tryline, it also counts as a five-pointer.
The scrum-half can feed the ball either side of the scrum
Why is the tackler penalised for not rolling away, yet the tackled player seems to be able to lay there with impunity once the ball has been released, preventing any chance for the defending side to heel the ball back?
Is there no law that says he should also roll away?
Bob Hayton, Maidstone
We have a checklist at the tackle which goes like this:
Tackler to release ball carrier and roll away
Ball carrier to release ball immediately and roll away
Arriving players to stay on their feet.
We tend to look more at the tackler than the ball carrier, but we should be consistent in applying those laws to the ball carrier too.
Which side do you put the ball in a scrum?
Sam Gamble, Newcastle Under Lyme
There is no right or wrong side to feed the ball into the scrum.