2018 NFL RULEBOOK Wrote:ARTICLE 2. REQUEST FOR REVIEW. A Replay Review will be initiated by a member of the Officiating department from a
location in the League office or a Replay Official from a Replay Booth comparable to the location of the coaches’ booth or Press
Box when the on-field ruling is:
(a) a score for either team;
(b) an interception;
© a fumble or backward pass that is recovered by an opponent or goes out of bounds through an opponent’s end zone;
(d) a muffed scrimmage kick recovered by the kicking team;
(e) after the two-minute warning of each half;
(f) throughout any overtime period; and
(g) any disqualification of a player.

There is no limit to the number of Replay Reviews that may be initiated by personnel designated in this Article. The ability of the designated personnel to initiate a review will be unrelated to the number of timeouts that either team has remaining, and no timeout will be charged for any review initiated pursuant to this Article. The designated personnel must initiate a review before the ball is next legally put in play.

https://operations.nfl.com/media/3277/20...ersion.pdf