Nice article.  For your rule of thumb section there is a third case.  For a future event that must happen x number of seconds&#x2F;minutes&#x2F;hours&#x2F;days into the future you want to store it as UTC and not wall time.<p>For example, the bypass valve on the boiler must be opened in 30 hours.  You want that as UTC instead of wall time as you don&#x27;t want a DST change to add an extra hour to that as you&#x27;d get a pile of scrap instead of an intact boiler.