Question:

Where may the mat be placed?

Answer:

The front edge of the mat must be not less than 2m from the rear ditch and not less than 23m from the front ditch and on the centre line of the rink of play.  Law 6.1.1

 

Question:

The jack is improperly rolled once by each opponent.  What action is taken?

Answer:

If the jack is improperly delivered once by each player in any end, it must not be delivered again in that end.  Instead, it must be centred with the nearest point of the jack to the mat line being 2 metres from the front ditch, and the mat must be placed as described in law 6.1.1 by the first player to play.  Law 10.3