A recent change that has been made to the game rules relates to the position of the landed jack and it is outlined in Article 7 of the International Rules:
3) That the jack must be a minimum of 50 cm from any obstacle and from the end line of the lane, it must also be a minimum of 1.5 metres from another circle or jack in use. (note: no minimum distance is required from the “side” line that separates the lanes or the dead ball lines at the side of the lanes).