day
Let an agent distinguish the day as a unit of time, as a solar period and as a calendar date, and handle time zones and daylight saving correctly.
Bundle → Layer → Finding → Questions Filled
4 bundles · 8 layers · 8 findings · 16 questions
Unit and astronomy The day as unit and as rotation.
Unit
Definition in seconds.
Unit definition
The unit and its relation to SI.
- Which definition of day applies here? definition
- Does the precision required make the difference matter? boundary
Astronomical day
Solar and sidereal days.
Astronomical basis
The astronomical day used.
- Is the solar or the sidereal day meant? definition
- How does day length vary over the year? measurement
Civil day Days in time zones.
Time zone
The zone the day belongs to.
Zone rules
The zone and its offset rules.
- In which time zone is this day reckoned? definition
- Does a daylight saving change fall on it? boundary
Day boundaries
Midnight and edge cases.
Boundary rules
When the day begins and ends.
- When does this day begin and end? definition
- How are events near midnight assigned? action
Counting days Durations and deadlines.
Durations
Calendar and business days.
Counting rule
Which days are counted.
- Are calendar days or business days counted? definition
- Which holidays are excluded, and in which jurisdiction? boundary
Deadlines
Day-based deadlines.
Deadline rule
How a day-count deadline is computed.
- How is this deadline computed in days? definition
- What happens when it falls on a non-working day? boundary
Naming Weekdays and dates.
Weekday
The day of the week.
Weekday naming
The weekday and numbering convention.
- Which weekday is this, and which numbering convention applies? definition
- Does the week start on Monday or Sunday here? boundary
Date
The calendar date.
Date identifier
The date naming this day.
- Which calendar date names this day? definition
- In which calendar? definition
Classifiers Filled
- Family
- Thing Registry
- Category
- Cross-cutting context
- Entry kind
- thing
- Plane
- XCT
- Domain
- XCT.TME
What it is Filled
A unit of time of 86,400 seconds, and the period of one rotation of the Earth relative to the Sun, reckoned from midnight to midnight in civil use.
Why it exists Filled
Let an agent distinguish the day as a unit of time, as a solar period and as a calendar date, and handle time zones and daylight saving correctly.
Distinguishing features Filled
- A unit of time and a solar cycle, which differ slightly
- The civil day follows a time zone and can be 23 or 25 hours on daylight saving changes
- Distinct from daytime, the light part of the day
- A calendar date names a particular day
What robots and AI may and may not do Filled
Must not
- Assume every day has 24 hours across daylight saving changes.
- Count calendar days where a rule specifies business days, or the reverse.
- Shift an event to a different day through a time zone error without flagging it.
Only with a human decision
- Deciding whether a legal or contractual deadline has passed.
May
- Count days for durations and deadlines, stating the time zone and calendar.
- Name dates and weekdays for its user.
Moral aspects Filled
- Deadlines measured in days decide rights, payments and appeals.
- Rest days and holy days matter to people and communities.
Who is affected
- People with deadlines
- Workers and their rest days
- Religious communities
Owners Filled
Steward
Nobody owns it; time authorities and governments set civil time and time zones.
Links to other meta-models Filled
parent
- Q2199864 - registry parent class
related
- unit of time - accepted for use with the SI
- calendar date - a date identifies one day
- hour - 24 hours in civil time
- daytime - daylight is only part of the day
What else AI and robots need to interact with it Filled
Identity and identifiers required Filled
- Vercy registry: vr.tr.day
- Wikidata: Q573 (https://www.wikidata.org/wiki/Q573)
- unit symbol: d accepted for use with the SI
Direct properties not applicable Not applicable
- length: 86400 s - SI day; mean solar day varies by milliseconds
- sidereal day: 86164.09 s - rotation relative to the stars
Plane XCT: no invented physical properties.
Recognition optional Filled
- Sunrise and sunset mark daylight, not the civil day
- Calendars show days as dates and weekdays
- Clocks reset at midnight in civil time
- Experienced as daylight and night; recorded on clocks and calendars.
Capabilities and actions required Filled
- count days, for durations and deadlines
- name days, with calendar dates and weekdays
- divide days, into hours, minutes and seconds
- adjust them, as with leap seconds and daylight saving shifts
Hazards and failure modes required Filled
- Assuming every day has 24 hours across daylight saving changes
- Confusing calendar days with business days in deadlines
- Time zone errors that move events to another day
Standards and interfaces required Filled
- SI Brochure, non-SI units accepted for use
- ISO 8601 for date and time representation
- National laws on time zones and daylight saving
Context of use required Filled
- Organising time for daily life, work, law and science.
- solar day, sidereal day, civil day
- working day, business day, calendar day
- by name: weekdays
Sources Filled
- Wikidata item Q573: day - identity and sense of the item
- Wikipedia: Day - general description of the item
Open questions
- Should the civil day and the solar day be separate entries?
- How should business days be modelled across jurisdictions with different holidays?
- How should agents present day counts that cross time zones?
Machine files
Provenance
thing registry research (pass 2) · unreviewed
Built from: models/things/publications/thing-q573/spec.json