11.3. Datetime Standards

  • Date and time formats varies from country to country [19]

11.3.1. Date

Formal date format in USA [26]:

4/12/61
April 12, 1961

Formal date format in Japan [25]:

61/04/12
1961年04月12日

20/12/31
平成20年12月31日

Formal date format in Germany:

12.04.1961

Date format in Poland:

12 kwietnia 1961
12 kwiecień 1961

12 IV 1961
12.IV.1961

12.4.1961
12.04.1961

12/4/1961
12/04/1961

12-04-1961
1961-04-12

Which format is a formal standard in Poland? [24]

11.3.2. Time

  • What AM stands for?

  • What PM stands for?

  • 24 and 12 hour clock

  • Zero padded minutes, seconds and microseconds but not hours

  • Variable length microseconds

  • Confusion at noon and midnight

24 and 12 hour clock:

5:00 AM
5:00 PM
5:00
17:00

Zero padded:

06:07
6:07

06:07:00
6:07:00

6:07:00.000001
6:07:00.123456
6:07:00.123
6:07:00.1

Noon and Midnight

  • Which time is a midnight?

  • Which time is a noon?

  • Confusion at noon and midnight [20]

  • Is 12:00 a noon (in 24h format), or someone just simply forgot to put AM/PM?

12:00 am
12:00 pm

12:00
24:00

00:00
0:00

11.3.3. Times after 24:00

  • Times after 24:00 [21]

  • UTC leap second [18]

  • Leap second discontinuation post 2035 [1]

  • Issues created by insertion (or removal) of leap seconds

  • Calculation of time differences and sequence of events

  • Missing leap seconds announcement

  • Implementation differences

  • Textual representation of the leap second

  • Binary representation of the leap second

  • Other reported software problems associated with the leap second

23:59:59
23:59:60

25:00
27:45

14:00-30:00

11.3.4. Decimal Time

  • Unix time gives date and time as the number of seconds since January 1, 1970

  • Microsoft's FILETIME as multiples of 100ns since January 1, 1601

  • VAX/VMS uses the number of 100ns since November 17, 1858

  • RISC OS the number of centiseconds since January 1, 1900

Source: [17]

11.3.5. Other

  • Military time [22]

  • Military time zones [23]

  • Swatch Internet Time - Beats @300 [7]

  • sidereal day on Earth is approximately 86164.0905 seconds (23 h 56 min 4.0905 s or 23.9344696 h)

11.3.6. Calendars

  • Julian Calendar [8]

  • Gregorian Calendar [3]

  • List of adoption dates of the Gregorian calendar by country [2]

  • There are only four countries which have not adopted the Gregorian calendar: Ethiopia (Ethiopian calendar), Nepal (Vikram Samvat and Nepal Sambat), Iran and Afghanistan (Solar Hijri calendar)

11.3.7. Astronomy

  • Synodic day - the period for a celestial object to rotate once in relation to the star it is orbiting [10]

  • Solar time - calculation of the passage of time based on the position of the Sun in the sky [9]

  • Epoch (astronomy) [5]

  • Sidereal Time [4]

  • JD - Julian Day [6]

11.3.8. Space Industry

  • UTC - Coordinated Universal Time [13]

  • GMT - Greenwich Mean Time [11]

  • MET - Mission Elapsed Time

  • Relativistic effects

  • Time dilatation due to speed approaching speed of light

11.3.9. Planet Mars

  • MSD - Mars Sol Date [15]

  • MTC - Coordinated Mars Time [16]

  • Timekeeping on Mars [14]

  • Mars Clock [12]

  • Martian sidereal day is 24 h 37 m 22.663 s (88,642.663 seconds)

  • Martian solar day is 24 h 39 m 35.244 s (88,775.244 seconds)

11.3.10. References