<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: 10pt; color: #000000"><div>Hello. </div><div><br data-mce-bogus="1"></div><div>I am a clinical biochemist and not well versed in handling the TZ database. I am investigating a software problem related to hospital patient data management that appears to be triggered when the software encounters a patient record with a date-of-birth that coincides with a historic daylight saving time Spring transition date. Through this investigation I have learned many details about the history of daylight saving time, but I often question the reliability of sources of information. It appears that many use the tz database as a source of truth. </div><div><br data-mce-bogus="1"></div><div>I am seeking assistance to query the tz database to determine the entries in the database for <!--StartFragment--><span style="color: #000000; font-family: arial, helvetica, sans-serif; font-size: 13.3333px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;" data-mce-style="color: #000000; font-family: arial, helvetica, sans-serif; font-size: 13.3333px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">Area /Location America/Regina to determine the (1) </span>daylight saving time Spring transition date and (2) daylight saving time Spring transition hour from 1900 to 1966. </div><div>I understand there were 10 years between 1930 and 1941 when the hour of Spring daylight saving transition was 0000 (midnight) to 0100. I would like to confirm these entries are in the tz database. I have numerous references that daylight saving time was also observed in America/Regina during world war ONE ( 1914-1918) and I am uncertain if those entries are in the tz database or the hour of those transitions. </div><div><br data-mce-bogus="1"></div><div>I am uncertain if it is appropriate to ask for this type of assistance on this discussion group. </div><div><br data-mce-bogus="1"></div><div>Thank-you very much, regards, Andrew</div><div><br data-mce-bogus="1"></div><div><br></div><div><br data-mce-bogus="1"></div><div>Dr. A.W. Lyon</div><div>Dept Pathology and Laboratory Medicine</div><div>University of Saskatchewan</div><div><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div></div></body></html>