2006 New York Code - Directional Sign Design.

 
    §  27-386 Directional sign design. Directional exit signs shall comply
  with all of the requirements for exit signs in section  27-385  of  this
  article,  and  shall  read  "EXIT"  with  a  horizontal  arrow or arrows
  indicating the direction to the exit or exits. However, when  the  arrow
  is  below the letters, the letters may be three and three-eighths inches
  high and nine-sixteenths inch strokes, except in  buildings  and  spaces
  classified in occupancy group F where they shall be at least five inches
  high  with  nine-sixteenths  inch  strokes. The arrow or arrows shall be
  red.