Tech/Basics/Time
Years, Months, Days, Hours, Minutes, Seconds, Daylight-Savings and Time-Zones
Computers are precise, the human calendar and time practices are not. There are large amounts of confusion.
Skew or Smear
Seconds or Minutes can be impacted by an under-documented process called "Skew" or "Smear" where a time jump is altered slowly over a period of days leading up to the jump. When the world is expecting a leap minute or a leap second I find it a bad idea to bend time and then offer no jump.
- No two skew or smear systems operate the same
- The use of differing time sources can cause conflict
- Add monitoring to your NTP server for drifts that defy logic.
TZ, Timezone, Time Zone, and Time-Zone
Announcing a date and time in your region does to automatically mean the reader in another timezone understands when it is supposed to be. Add Timezone information to communications and or confirm that the systems add it for you.
Years
Not every person on the planet uses the same year system. We need people to start mentioning which calendar system they use with a date. It may be useful to define the use of Gregorian Calendar in documentation. In 2016 Saudi Arabia adopted the Gregorian Calendar.
Months
While 12 months is common on many calendars they do not all start and end at the same place. Be careful.
Days
Leap days happen. Don't be Microsoft. Read more and note that more recently sub-pages had to be added due to the increase of events. https://en.wikipedia.org/wiki/Leap_year_problem#Occurrences
Hours
Is noon 12 AM or 12 PM? Watch UI people mess with this and confuse users. Try using 24 hours in timestamps, it helps.
Minutes
Looking to leap days and leap seconds you could correctly guess that minute calculations have been ruined when calculating reverse and forward duration. You would be correct.
Daylight Savings
Humans are great at really screwing things up. Moving an hour or more twice a year is a great way to make computers mad. In Chile I had to get good at editing time zone software as the government changed Daylight Savings times five times in 2010 which meant 10 day changes.