STANDARDS SECTION XVIII - TOURNAMENT STANDARDS OF PERFORMANCE may call for a review, and the result of the review will not affect the remaining  challenges of either player. The decision of the Electronic Review is final and cannot be appealed. In the  situation where the written ruling (IN/OUT) on the video board differs from  the graphic shown (ball mark digital imagery), then the ball mark imagery  determines whether the ball is IN or OUT, not the written ruling, however, the  Chair Umpire must contact the review official to get the final confirmation on  the call. A certified official, approved by the Supervisor, shall act as the review official,  whose duties shall include, but are not limited to: 9.  Final Decision 10. Review Official a.  Determining which impact shall be reviewed by the system. b.  Monitoring the system to ensure it is functioning properly. c.  Notifying the Chair Umpire immediately in the case of a system failure  or any other condition that prohibits or brings into question the ability  of the system to review a challenged call. In this case, the Chair Umpire  immediately shall notify both players that review is not available until  further notice. d. Acting as the final authority on the number of challenges each player  has remaining. Communicating with the Chair Umpire, at first possible  opportunity, when one (1) challenge is left, and confirming the one (1)  remaining challenge. The review official and supporting technology staff shall be located within  the stadium or arena in a secured area and with an unobstructed view of the  court. For each court that is using a review system, there shall be a minimum of one  (1) video board, of sufficient size, located in a position where the Chair Umpire,  players, and spectators may view the results of the challenge. The following specifications are recommended for the electronic system  review booth:  11. Video Board 12. Review Booth  369