(a) A stone which comes to rest biting or in front of the hog line after making contact with a stone in the FGZ is considered to be in the FGZ.
(b) A stone that comes to rest outside the house but biting the tee line is not considered to be in the FGZ.
(a) Any stationary stone(s) belonging to the opposition located in the FGZ shall not be removed from play by the delivering team prior to the delivery of the sixth stone of the end.
(b) When an opposition’s stone(s) is removed from play from the FGZ prior to the sixth stone of the end, directly or indirectly and without exception, the delivered stone must be removed from play and any other displaced stones replaced as close as possible to their original position(s).
(c) Any stone previously in the FGZ, whose location is now not in the FGZ – as per rule 12(1)(a) or (b) – may be removed at any time without penalty.
(d) A delivered third, fourth or fifth stone of an end may hit an opposition stone(s) located in the FGZ on to a stone(s) not in the FGZ providing that any opposition stone originally located in the FGZ remains in play. If an opposition’s stone(s) is removed from play, apply Rule 12(2)(b).
(e) A team may remove their own stone from the FGZ providing its removal does not cause an opposition stone to be removed from play from the FGZ. If an opposition’s stone(s) is removed from play, apply Rule 12(2)(b).
(f) A team may raise their stone located in the FGZ on to an opposition stone located in the house (not in the FGZ) and remove it from play. If an opposition’s stone(s) in the FGZ is removed from play during the execution of the raise, then apply Rule 12(2)(b).
(3) After the delivery of each of the first four stones of an end, it is the responsibility of the skip of the team who is about to deliver to ensure agreement with the opposing skip as to whether or not any of the stone(s) in play have come to rest in the FGZ. If they cannot agree, they shall make the determination by using the six-foot measuring stick. If the position of another stone(s) hinders the use of the six-foot measure, they may reposition the stone(s), complete the measurement and replace the stone(s) to its original position.
(4) Visual agreement by the opposing skips as to whether or not one of the first four stones of the end was in the FGZ, does not preclude a measurement occurring at the conclusion of the end involving the same stone(s).There you have it - everything you wanted to know about the "Free Guard Zone" but were afraid to ask.