A client born in Ecuador wrote to me: "I need a little help with something plus I don't know who else can help me besides Astro! When I was born, the President of Ecuador changed the time zone (one hour ahead) from Nov/28/1992 to Feb/05/1993 because of problems with energy and there were a lot of power cuts across the country. " I checked the tzdata/southamerica file which holds for Ecuador: # Ecuador # # Milne says the Central and South American Telegraph Company used -5:24:15. # # From Paul Eggert (2007-03-04): # Apparently Ecuador had a failed experiment with DST in 1992. # <http://midena.gov.ec/content/view/1261/208/> (2007-02-27) and # <http://www.hoy.com.ec/NoticiaNue.asp?row_id=249856> (2006-11-06) both # talk about "hora Sixto". Leave this alone for now, as we have no data. # # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Guayaquil -5:19:20 - LMT 1890 -5:14:00 - QMT 1931 # Quito Mean Time -5:00 - ECT # Ecuador Time The two links in the comment to not work. I search the web and came up with this link: http://www.elcomercio.com/actualidad/hora-sixto-1993.html which says: Al inicio de su mandato, el Gobierno Nacional, mediante Decreto Presidencial no. 285, obligó que todos los ecuatorianos adelantaran una hora en sus relojes para “ aprovechar la luz solar” y disminuir el consumo de energía. Fue la llamada ‘hora de Sixto’, que se aplicó desde el 28 de noviembre de 1992 hasta el 5 de febrero de 1993. Incluso, los estudiantes de todos los niveles educativos estuvieron obligados a iniciar clases a las 06:00 y terminar antes del mediodía. Google translation: At the beginning of his term, the National Government, through Presidential Decree no. 285, forced all Ecuadorians to advance an hour in their watches to "take advantage of sunlight" and reduce energy consumption. It was the so-called 'Sixtus hour', which was applied from November 28, 1992 until February 5, 1993. Even students of all educational levels were forced to start classes at 06:00 and finish before midday. There should probably be a rule: Rule ECU 1992 only - Nov 28 0:00 1:00 S Rule ECU 1993 only - Feb 5 0:00 0 - and the last lines of the existing entry should refer to this rule. Whether the law applied also to Galapagos, I do not know.