The schedule of Ramadan (the Islamic calendar month) may be delayed or extended in countries which use a physical sighting of the crescent moon to end the month, and can even differ by country if they go to different astronomers. This wouldnt affect DST I think, but more the timezone info - database. https://www.reuters.com/article/us-europe-islam-ramadan-idUS... https://www.economist.com/the-economist-explains/2018/06/12/...