law: Weekly Holidays Act, 1942
  3. Closing of shop
  (1) Every shop shall remain entirely closed on one day of the
  
  week, which day shall be specified by the shop-keeper in a notice permanently
  
  exhibited in a conspicuous place in the shop.
  (2) The day so specified shall not be altered by the shop-keeper
  
  more often than once in three months.