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Published

February 28

vr.tr.february-28 · thing-q2362

Let an agent handle February 28 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 February 28 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 February 28 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 February 28, 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 February 28? 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

February 28, day 59 of the year in the Gregorian calendar, with 306 days remaining (307 in leap years). In leap years it is followed by February 29.

Why it exists Filled

Let an agent handle February 28 as a calendar date with weekday computation, observances attributed to their traditions and sourced events.

Distinguishing features Filled

  • The twenty-eighth day of February
  • 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

  • Treat February 28 and February 29 as interchangeable when calculating legal deadlines, ages or contracts.
  • Assign events to the date without a reliable source.
  • Present an observance of one country as universal.

Only with a human decision

  • Deciding how a leap-day birthday or deadline falls in a non-leap year when the law is unclear.

May

  • Report the date's position in the year and its relation to February 29 in leap years.
  • Handle leap-year date logic correctly when scheduling or calculating durations.

Moral aspects Filled

  • Date arithmetic errors around the end of February can cause missed deadlines and payments.
  • People born on February 29 depend on fair handling of non-leap years.

Who is affected

  • People with deadlines or birthdays near leap day
  • Systems users relying on correct dates

Owners Filled

Steward

Nobody: a calendar date held in common.

Links to other meta-models Filled

parent

  • Q11187366 - registry parent class

related

  • February - month
  • February 27 - 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.february-28
  • Wikidata: Q2362 (https://www.wikidata.org/wiki/Q2362)
  • ISO 8601: --02-28 recurring date

Direct properties not applicable Not applicable

  • day of year: 59 day
  • days remaining: 306 or 307 days - common or leap year

Plane XCT: no invented physical properties.

Recognition optional Filled

  • Written 28 February or February 28
  • ISO format --02-28
  • 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 Q2362: February 28 - identity and sense of the item
  2. Wikipedia: February 28 - 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-q2362/spec.json