← Back to catalogue
Published

April 9

vr.tr.april-9 · thing-q2504

Let an agent handle April 9 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 April 9 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 April 9 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 April 9, 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 April 9? 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

April 9, day 99 (day 100 in leap years) of the year in the Gregorian calendar, with 266 days remaining in both common and leap years. Observances on this date vary by country and tradition.

Why it exists Filled

Let an agent handle April 9 as a calendar date with weekday computation, observances attributed to their traditions and sourced events.

Distinguishing features Filled

  • The ninth day of April
  • 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

  • Invent observances for April 9 where none are sourced.
  • Report on-this-day events without sources.
  • Mix Julian and Gregorian dates for historical events on April 9 without saying which.

Only with a human decision

  • Scheduling legally binding deadlines that fall on this date.

May

  • Compute the day of the year and weekday for April 9 in a given year.
  • List observances on April 9 only with the country or tradition and a source.

Moral aspects Filled

  • Anniversaries of tragedies on a date deserve respectful treatment.
  • Invented observances spread misinformation.

Who is affected

  • Readers relying on calendars
  • Communities marking anniversaries

Owners Filled

Steward

Nobody owns a date; calendar standards define it and the public holds it in common.

Links to other meta-models Filled

parent

  • Q11188523 - registry parent class

related

  • April - month
  • April 8 - 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.april-9
  • Wikidata: Q2504 (https://www.wikidata.org/wiki/Q2504)
  • ISO 8601: --04-09 recurring date

Direct properties not applicable Not applicable

  • day of year: 99 or 100 day - common year, leap year where different
  • days remaining: 266 days

Plane XCT: no invented physical properties.

Recognition optional Filled

  • Written 9 April or April 9
  • ISO format --04-09
  • 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 Q2504: April 9 - identity and sense of the item
  2. Wikipedia: April 9 - 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-q2504/spec.json