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Published

April 30

vr.tr.april-30 · thing-q2536

Let an agent handle April 30 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 30 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 30 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 30, 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 30? 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 30, day 120 (day 121 in leap years) of the year in the Gregorian calendar, with 245 days remaining in both common and leap years. Observances on this date vary by country and tradition; it is Walpurgis Night in parts of northern and central Europe and International Jazz Day.

Why it exists Filled

Let an agent handle April 30 as a calendar date with weekday computation, observances attributed to their traditions and sourced events.

Distinguishing features Filled

  • The thirtieth 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

  • Present Walpurgis Night or other regional customs on April 30 as observed everywhere.
  • List on-this-day events for April 30 without checking them against sources.
  • Convert Julian-calendar April 30 dates to Gregorian without stating it.

Only with a human decision

  • Fixing deadlines or legal dates that fall on April 30 when a public holiday may move them.

May

  • Compute the day of year for April 30 and adjust correctly for leap years.
  • List observances on April 30, such as Walpurgis Night or International Jazz Day, with the countries or bodies that mark them.

Moral aspects Filled

  • Calendar facts feed schedules and legal deadlines, so errors cost people.
  • Customs tied to the date belong to particular communities and should be described with respect.

Who is affected

  • People keeping deadlines
  • Communities that observe the date
  • Readers

Owners Filled

Steward

Nobody: a calendar date held in common.

Links to other meta-models Filled

parent

  • Q11187571 - registry parent class

related

  • April - month
  • April 29 - 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-30
  • Wikidata: Q2536 (https://www.wikidata.org/wiki/Q2536)
  • ISO 8601: --04-30 recurring date

Direct properties not applicable Not applicable

  • day of year: 120 or 121 day - common year, leap year where different
  • days remaining: 245 days

Plane XCT: no invented physical properties.

Recognition optional Filled

  • Written 30 April or April 30
  • ISO format --04-30
  • 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 Q2536: April 30 - identity and sense of the item
  2. Wikipedia: April 30 - 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-q2536/spec.json