I recently proposed some tz database changes for Prague; see <https://en.wikipedia.org/wiki/Tz_database> and <https://mm.icann.org/pipermail/tz/2018-April/026415.html>. I used your web page <https://kalendar.beda.cz/kdy-zacina-a-konci-letni-cas> as the main source for these fixes; thank you! I noticed what appears to be a typographical error in your web page. It says: 1946-7 zimní čas 1. prosinec (2:00) 23. únor (2:00) However, the primary source <http://ftp.aspi.cz/opispdf/1946/092-1946.pdf> says: "§1. Počátek zimního času v roce 1946 se určuje na den 1. prosince 1946 o třetí hodiné ranní středoevropského času a provede se posunutím hodinových ručiček na druhou hodinu." Google Translate suggests this means the transition was December 1 at 03:00, not December 1 at 02:00. That is, the clock was 03:00 before the transition, and 02:00 afterwards. The attached patch contains a proposed fix to kalendar.beda.cz. I am CC:ing this to the time zone mailing list to give them a heads-up as to why I made this change in the tz database.