December 20
Let an agent handle December 20 as a calendar date with weekday computation, observances attributed to their traditions and sourced events.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent handle December 20 as a calendar date with weekday computation, observances attributed to their traditions and sourced events.
December 20, day 354 (day 355 in leap years) of the year in the Gregorian calendar, with 11 days remaining in both common and leap years. December 20 is International Human Solidarity Day, observed by the United Nations, and the anniversary of the formal transfer of Louisiana to the United States in New Orleans in 1803, South Carolina s secession in 1860 and the handover of Macau to China in 1999.
What it is for: A calendar date for scheduling, holidays and anniversaries.
It can be compute its weekday in a given year; check local and international observances; find sourced historical events; schedule events.
Distinguishing features
The twentieth day of December
Weekday varies by year
Observances vary by place
Julian and Gregorian dates differ by 13 days in this era
What it looks like
A date on calendars.
Physical character
day of year: 354 or 355 day - common year, leap year where different
days remaining: 11 days
How it is recognised
Written 20 December or December 20
ISO format --12-20
Observances vary by country and tradition
Related models
is part of - month
follows - date
is a kind of - category
is expressed in - notation
In practice
Families and kinds
the recurring calendar date
specific dated days in given years
Identifiers
ISO 8601 --12-20 recurring date
Standards and regulation
ISO 8601
National public holiday laws
Failure modes and hazards
Assuming observances are universal
Unsourced on-this-day events
Mixing Julian and Gregorian dates
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Date Calendar facts.
Calendar arithmetic.
Weekday
Computation.
Weekday
Weekday.
- On which weekday does December 20 fall in this year? measurement
- Is it a leap year? boundary
Calendar
Julian or Gregorian.
Calendar
Calendar system.
- Is the Julian or Gregorian calendar meant? boundary
- What is the equivalent date in the other calendar? measurement
Observances Holidays.
Observances vary.
Holiday
Public holiday.
Holiday
Holiday status.
- Is December 20 a public holiday or observance here? provenance
- Which tradition or law sets it? provenance
Attribution
Traditions.
Attribution
Attributed observances.
- Which countries or communities observe something on this date, according to them? provenance
- Is the observance attributed rather than assumed? boundary
History Past events.
Events need sources.
Events
On this day.
Events
Historical events.
- Which notable events happened on December 20, according to reliable sources? provenance
- Are dates given in the same calendar? boundary
Anniversaries
Recurring.
Anniversaries
Anniversaries.
- Which anniversaries fall on this date this year? provenance
- Which are round numbers? measurement
Planning Scheduling.
Dates drive plans.
Countdown
Days until.
Countdown
Countdown.
- How many days until the next December 20? measurement
- From which date? definition
Work
Working day.
Work
Working day.
- Is it a working day for this organisation? provenance
- Do deadlines move? boundary
What the second pass must settle
- Should dated days be separate entries?
- How should observances be linked?
- How should events be sourced?