How is the national electoral register created?

Sweden,The Election Act (2005: 837), 'Chapter 5: Electoral rolls', <Sweden_Election_Act_2005 _am2014_en%20(1).pdf> , accessed 4 September 2018

The central election authority shall for each electoral district prepare a list of those who are entitled to vote in the election (electoral roll) based on the information that, 30 days prior to the election day, is contained in the population registration database.