title: Date of birth: Same date of birth in every local?
body: <p>Currently im storing the date of birth of a user in milliseconds (since 01.01.1970). Do i have to ensure that it is the same date of birth in every country or is it common that it can happen that it is the 11th November in country X and the 12th November in country Y?</p>
  
  <p>If instead it is common practice to have the exact same date of birth in each country, how could i ensure that the milliseconds i store always point to the exact same day of month in each country?</p>