law: Factories Act, 1948 
  3. References to time of day 
  In this Act references to time of day are references to Indian
  
  Standard Time, being five and a half hours ahead of Greenwich Mean Time:
  PROVIDED  that for any area in which Indian Standard
  
  Time is not ordinarily observed the State Government may make rules,- 
  (a) specifying the area,
  (b) defining the local mean time ordinarily observed therein,
  
  and
  (c) permitting such time to be observed in all or any of the
  
  factories situated in the area.