body: With regard to the Brexit today, I was asking myself when exactly it goes into effect. It should be 31st January, 2020, 23:59:59, but which time zone?
  
  
  This leads me to the question, if there is an official - or default - time zone in the EU or even worldwide when a contract states a start or end date?
  
  
  Is it undefined unless the contract specifies it?
  
  
  P.S.: Not sure if this is more a political question..?
  
  
  
title: Is there an "official time" in the EU, and if so, which is it?