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Published

December 21

vr.tr.december-21 · thing-q2603

Let an agent handle December 21 as a calendar date with weekday computation, observances attributed to their traditions and sourced events.

Thing Registry Cross-cutting context XCT.TME
Bundle → Layer → Finding → QuestionsClassifiersWhat it isWhy it existsDistinguishing featuresWhat robots and AI may and may not doMoral aspectsOwnersLinks to other meta-modelsIdentity and identifiersDirect propertiesRecognitionCapabilities and actionsHazards and failure modesStandards and interfacesContext of useSources

Bundle → Layer → Finding → Questions Filled

4 bundles · 8 layers · 8 findings · 16 questions

Date Calendar facts.

Weekday

Computation.

Weekday

Weekday.

  1. On which weekday does December 21 fall in this year? measurement
  2. Is it a leap year? boundary

Calendar

Julian or Gregorian.

Calendar

Calendar system.

  1. Is the Julian or Gregorian calendar meant? boundary
  2. What is the equivalent date in the other calendar? measurement
Observances Holidays.

Holiday

Public holiday.

Holiday

Holiday status.

  1. Is December 21 a public holiday or observance here? provenance
  2. Which tradition or law sets it? provenance

Attribution

Traditions.

Attribution

Attributed observances.

  1. Which countries or communities observe something on this date, according to them? provenance
  2. Is the observance attributed rather than assumed? boundary
History Past events.

Events

On this day.

Events

Historical events.

  1. Which notable events happened on December 21, according to reliable sources? provenance
  2. Are dates given in the same calendar? boundary

Anniversaries

Recurring.

Anniversaries

Anniversaries.

  1. Which anniversaries fall on this date this year? provenance
  2. Which are round numbers? measurement
Planning Scheduling.

Countdown

Days until.

Countdown

Countdown.

  1. How many days until the next December 21? measurement
  2. From which date? definition

Work

Working day.

Work

Working day.

  1. Is it a working day for this organisation? provenance
  2. Do deadlines move? boundary

Classifiers Filled

Family
Thing Registry
Category
Cross-cutting context
Entry kind
thing
Plane
XCT
Domain
XCT.TME

What it is Filled

December 21, day 355 (day 356 in leap years) of the year in the Gregorian calendar, with 10 days remaining in both common and leap years. December 21 is the usual date of the December solstice, the shortest day in the Northern Hemisphere, observed in festivals from Yalda in Iran to Dongzhi in East Asia, and the anniversary of the Lockerbie bombing of Pan Am Flight 103 in 1988, of the Pilgrims landing at Plymouth in 1620 by one reckoning, and of the first crossword puzzle published in 1913.

Why it exists Filled

Let an agent handle December 21 as a calendar date with weekday computation, observances attributed to their traditions and sourced events.

Distinguishing features Filled

  • The twenty-first day of December
  • Weekday varies by year
  • Observances vary by place
  • Julian and Gregorian dates differ by 13 days in this era

What robots and AI may and may not do Filled

Must not

  • Present the solstice as always on December 21.
  • Present northern winter festivals as universal when it is summer in the south.
  • List on-this-day events without a source.
  • Mix Julian and Gregorian dates for events before the calendar change.

Only with a human decision

  • Scheduling public messages tied to a religious or cultural solstice festival.

May

  • Give the day number of December 21 and its observances, such as solstice festivals like Yalda and Dongzhi.
  • Note that the solstice falls on December 21 or 22 depending on the year and time zone.

Moral aspects Filled

  • Solstice festivals carry religious and cultural meaning for many peoples.
  • Northern seasonal framing overlooks the Southern Hemisphere.

Who is affected

  • Communities that hold solstice festivals
  • People in the Southern Hemisphere
  • Readers

Owners Filled

Steward

Nobody: the public calendar held in common; each observance belongs to the body that set it.

Links to other meta-models Filled

parent

  • Q11187254 - registry parent class

related

  • December - month
  • December 20 - date
  • calendar date - category
  • ISO 8601 - notation

What else AI and robots need to interact with it Filled

Identity and identifiers required Filled

  • Vercy registry: vr.tr.december-21
  • Wikidata: Q2603 (https://www.wikidata.org/wiki/Q2603)
  • ISO 8601: --12-21 recurring date

Direct properties not applicable Not applicable

  • day of year: 355 or 356 day - common year, leap year where different
  • days remaining: 10 days

Plane XCT: no invented physical properties.

Recognition optional Filled

  • Written 21 December or December 21
  • ISO format --12-21
  • Observances vary by country and tradition
  • A date on calendars.

Capabilities and actions required Filled

  • compute its weekday in a given year
  • check local and international observances
  • find sourced historical events
  • schedule events

Hazards and failure modes required Filled

  • Assuming observances are universal
  • Unsourced on-this-day events
  • Mixing Julian and Gregorian dates

Standards and interfaces required Filled

  • ISO 8601
  • National public holiday laws

Context of use required Filled

  • A calendar date for scheduling, holidays and anniversaries.
  • the recurring calendar date
  • specific dated days in given years

Sources Filled

  1. Wikidata item Q2603: December 21 - identity and sense of the item
  2. Wikipedia: December 21 - general description of the item

Open questions

  • Should dated days be separate entries?
  • How should observances be linked?
  • How should events be sourced?

Machine files

Card as JSON Specification Card backlog vercy.card/1

Provenance

thing registry research (pass 2) · unreviewed

Built from: models/things/publications/thing-q2603/spec.json