January 1
Let an agent handle January 1 as a calendar date with weekday computation, observances, legal effects 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 January 1 as a calendar date with weekday computation, observances, legal effects and sourced events.
The first day of the year in the Gregorian calendar, with 364 days remaining (365 in leap years), observed as New Year Day and a public holiday in most countries; also observed as the World Day of Peace in the Catholic Church.
What it is for: Start of the calendar year, holidays and legal effective dates.
It can be compute its weekday in a given year; list observances and closures; check laws taking effect on January 1; find sourced historical events.
Distinguishing features
First day of the Gregorian year
Public holiday in most countries
Common effective date for laws
Other calendars have different new years
What it looks like
A date on calendars, often marked by celebrations.
Physical character
day of year: 1 day
days remaining: 364 or 365 days - common or leap year
How it is recognised
Written 1 January or January 1
ISO format --01-01
Other calendars start the year on different dates
Related models
is part of - month
is observed as - holiday
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 --01-01 recurring date
Standards and regulation
ISO 8601
National public holiday laws
Failure modes and hazards
Assuming all cultures celebrate the new year on this date
Year-boundary software bugs
Unsourced events
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 January 1 fall in this year? measurement
- Is the year a leap year? boundary
Software
Year boundaries.
Software
Year-boundary handling.
- Does software handle the year change and week numbering correctly? boundary
- Which ISO week does January 1 fall in? measurement
Observances New Year.
Most countries mark the day.
Holiday
Public holiday.
Holiday
New Year Day.
- Is January 1 a public holiday here, and what closes? provenance
- Is there a substitute day if it falls on a weekend? provenance
Other new years
Calendars.
Other new years
Other new years.
- Which communities celebrate the new year on other dates? provenance
- When are they this year? measurement
Law Effective dates.
Many rules start on January 1.
Effective
New rules.
Effective
Laws in force.
- Which laws or rates take effect on January 1 this year? provenance
- From which official source? provenance
Tax year
Fiscal years.
Tax
Tax year.
- Does the tax year start on January 1 here? provenance
- What deadlines follow? measurement
History Past events.
Events need sources.
Events
On this day.
Events
Historical events.
- Which notable events happened on January 1, according to reliable sources? provenance
- Are dates in the same calendar? boundary
Origin
Why January.
Origin
Origin.
- Why does the year begin on January 1 in the Gregorian calendar? provenance
- When did different countries adopt it? provenance
What the second pass must settle
- Should dated days be separate entries?
- How should other new years be linked?
- How should laws effective on January 1 be tracked?