ISO_8601.md

ISO Date Time Standards

Below are the basics of the ISO 8601 Date / Time specification

Dates

Calendar date ✅

1. Complete Representations

• Basic: YYYYMMDD ✅
• Extended: YYYY-MM-DD ✅

2. Reduced Accuracy

• Specific Month
  • Basic: YYYY-MM ✅
• Specific Year
  • Basic: YYYY ✅
• Specific Century
  • Basic: YY ✅

Ordinal Date

1. Complete Representations

• Basic: YYYYDDD ✅
• Extended: YYYY-DD ✅

Week Date

1. Complete Representation

• Basic: YYYYWwwD ✅
• Extended: YYYY-Www-D ✅

2. Reduced Accuracy

• Basic: YYYYWww ✅
• Extended: YYYY-Www ✅

Time of Day

Local Time

1. Complete Representations

• Basic: hhmmss ✅
• Extended: hh:mm:ss ✅

2. Reduced Accuracy

• Specific Minute
  • Basic: hhmm ✅
  • Extended: hh:mm ✅
• Specific Hour
  • Basic: hh ✅

3. Decimal Fractions

• A minimum of 1 digit after the decimal point, up to as many as needed.
• Fraction of Second
  • Basic: hhmmss,ss or hhmmss.ss ✅
  • Extended: hh:mm:ss,ss or hh:mm:ss.ss ✅
• Fraction of Minute
  • Basic: hhmm,ss or hhmm.mm ✅
  • Extended: hh:mm,mm or hh:mm.mm ✅
• Fraction of hour
  • Basic: hh,hh or hh.hh ✅

Time designator

• Any local time may be preceded bt the time designator: T ✅
• If the context is ambiguous, the time must be preceeded by T ✅

Beginning / End of Day

1. Beginning

• Basic: 000000 ✅
• Extended: 00:00:00 ✅

2. End

• Basic: 240000 ✅
• Extended: 24:00:00 ✅

UTC of day

1. Basic

• hhmmssZ ✅
• hhmmZ ✅
• hhZ ✅

2. Extended

• hh:mm:ssZ ✅
• hh:mmZ ✅

Difference between UTC and local

1. Basic

• hhmmss+hhmm or hhmmss-hhmm ✅
• hhmmss+hh or hhmmss-hh ✅

2. Extended

• hh:mm:ss+hh:mm or hh:mm:ss-hh:mm ✅
• hh:mm:ss+hh or hh:mm:ss-hh ✅

Date and Time

Complete Representations

1. Basic

• YYYYMMDDThhmmss ✅
• YYYYMMDDThhmmssZ ✅
• YYYYMMDDThhmmss±hhmm ✅
• YYYYMMDDThhmmss±hh ✅

2. Extended

• YYYY-MM-DDThh:mm:ss ✅
• YYYY-MM-DDThh:mm:ssZ ✅
• YYYY-MM-DDThh:mm:ss±hh:mm ✅
• YYYY-MM-DDThh:mm:ss±hh ✅

Non-Complete Representations

Combinations of date ant time formats defined above

• rules above are applied ✅
• does not qualify as a complete date and time ✅
• the date does not have reduced accuracy
• completely in basic, or completely in extended format Examples:

1. Calendar date and local time

• Basic: YYYYMMDDThhmm ✅
• Extended: YYYY-MM-DDThh:mm ✅

2. Ordinal date and UTC of day

• Basic: YYYYDDDThhmmZ ✅
• Extended: YYYY-DDDThh:mmZ ✅

3. Week date and local time and the difference from UTC

• Basic: YYYYWwwDThhmm±hhmm ✅
• Extended: YYYY-Www-DThh:mm±hh ✅

Time Interval

1. A start and an end - Basic: YYYYMMDDThhmmss/YYYYMMDDThhmmss - Extended: YYYY-MM-DDThh:mm:ss/YYYY-MM-DDThh:mm:ss
2. A duration and context info (only duration provided by ISO str) - Basic/Extended:
   • PnnYnnMnnDTnnHnnMnnS
   • PnnW - Alternate:
   • Basic: PYYYYMMDDThhmmss
   • Extended: PYYYY-MM-DDThh:mm:ss
3. A start and a duration - Basic:
   • YYYYMMDDThhmmss/PnnYnnMnnDTnnHnnMnnS
   • YYYYMMDDThhmmss/PYYYYMMDDThhmmss - Extended:
   • YYYY-MM-DDThh:mm:ss/PnnYnnMnnDTnnHnnMnnS
   • YYYY-MM-DDThh:mm:ss/PYYYY-MM-DDThh:mm:ss
4. A duration and an end - Basic:
   • PnnYnnMnnDTnnHnnMnnS/YYYYMMDDThhmmss
   • PYYYYMMDDThhmmss/YYYYMMDDThhmmss - Extended:
   • PnnYnnMnnDTnnHnnMnnS/YYYY-MM-DDThh:mm:ss
   • PYYYY-MM-DDThh:mm:ss/YYYY-MM-DDThh:mm:ss