Section 152. Promotion

The  town  board may determine that promotions of
  officers and members of such police department shall be made by the town
  board on the basis of seniority, meritorious police service and superior
  capacity as shown by competitive examination,  such  examination  to  be
  conducted  by  the appropriate civil service commission. Individual acts
  of personal bravery may be treated as an element of meritorious  service
  in such examination. The town board shall keep a complete service record
  of each member of such police department in accordance with the rules of
  the  appropriate  civil service commission and shall transmit the record
  of each candidate for promotion to  such  civil  service  commission  in
  advance of such examination.