I just found the date daylight savings ended in Iran in 1978. This is from the major Iranian newspaper Ettela'at, dated 1968-08-03, page 32. It looks like they decided to get the clocks back to +4:00 just in time for Ramadan that year: "Tomorrow Night, Pull the Clocks Back by One Hour At 1 o'clock in the forenoon of Saturday 14 Mordad [=1978-08-05], the clocks will be pulled one hour back and instead of 1 o'clock in the forenoon, Radio Iran will announce 24 o'clock. This decision was made in the Cabinet of Ministers meeting of 25 Tir [=1978-07-16], [...] At the beginning of the year 2537 [=March 1978: Iran was using a different year number for a few years then, based on the Coronation of Cyrus the Great], the country's official time was pulled forward by one hour and now the official time is one hour and a half ahead compared to last year, because in Farvardin of last year [=March 1977], the official time was pulled forward one hour and this continued until the second half of last year [=September 1977] until in the second half of last year the official time was pulled back half an hour and that half hour still remains." This matches the time of the true noon published in the newspapers, as they clearly go from +05:00 to +04:00 after that date (which happened during a long weekend in Iran). This means tzdata needs to fix the end of daylight saving in Iran for 1978 from October 20 to August 5. Thanks again, Roozbeh