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time

vr.tr.time · thing-q11471

Let an agent handle time as instants, durations and intervals with units, time scales and zones, and avoid the classic errors of mixing them.

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

Kind of time value Instant, duration or interval.

Instant

A point in time.

Instant

The instant and its zone.

  1. Is this an instant, and in which time zone or scale? definition
  2. How precise is it? measurement

Duration

A length of time.

Duration

The duration and unit.

  1. What duration is meant, in which unit? measurement
  2. Does it cross a daylight saving change? boundary
Scales and zones Which clock.

Time scale

UTC, TAI, GPS.

Time scale

The scale used.

  1. Which time scale is used? definition
  2. How are leap seconds handled? boundary

Time zone

Local time.

Zone

The zone and rules.

  1. Which IANA time zone applies? definition
  2. Have the zone rules changed recently? provenance
Measurement Clocks and synchronisation.

Clock

Reference and accuracy.

Clock source

The reference clock.

  1. Which clock or reference produced this time? provenance
  2. How accurate is it? measurement

Synchronisation

NTP, PTP, GNSS.

Synchronisation

How clocks agree.

  1. How are clocks synchronised? definition
  2. What is the maximum offset between systems? measurement
Use Scheduling and ordering.

Scheduling

Across zones.

Schedule

Schedule and zone handling.

  1. In which zone should this event be shown to each participant? action
  2. What happens at daylight saving changes? boundary

Ordering events

Causality in systems.

Ordering

How events are ordered.

  1. Can timestamps be trusted to order these events? boundary
  2. Is a logical clock needed? definition

Classifiers Filled

Family
Thing Registry
Category
Cross-cutting context
Entry kind
thing
Plane
XCT
Domain
XCT.TME
Other names and narrower kinds
paid time off, real-time, Moscoso, crystallization time, biological half-life, Döp, plasma half-life, Trading day, late, graduation time, local time, Rancata

What it is Filled

The continuing progression of events from past through present to future, measured in seconds and larger units, and used to order events and measure durations.

Why it exists Filled

Let an agent handle time as instants, durations and intervals with units, time scales and zones, and avoid the classic errors of mixing them.

Distinguishing features Filled

  • Instant, duration and interval are different things
  • Time scales differ: TAI, UTC, GPS time, local time
  • Local time depends on zone and daylight saving
  • Domain-specific times such as half-lives are durations

What robots and AI may and may not do Filled

Must not

  • Mix local times and UTC in one record without labels.
  • Ignore daylight saving changes when scheduling.
  • Alter timestamps in logs or records after the fact.
  • Change the clock of a system it does not administer.

Only with a human decision

  • Adjusting clocks in systems where time stamps carry legal or safety meaning.

May

  • Record times with time zone or in UTC and synchronise clocks it is authorized to manage.
  • Convert between time zones using an up-to-date time zone database.

Moral aspects Filled

  • Timestamps are evidence, and tampering with them can deny people justice.
  • Errors in time can make people miss medicines, trains or court dates.

Who is affected

  • People relying on schedules
  • System operators

Owners Filled

Steward

Nobody owns time; national metrology institutes keep official time.

Links to other meta-models Filled

parent

  • Q133250 - registry parent class

related

  • day, week, year - calendar units
  • clock - instruments
  • event - events occur in time
  • calendar date - a date is a whole day, not an instant

What else AI and robots need to interact with it Filled

Identity and identifiers required Filled

  • Vercy registry: vr.tr.time
  • Wikidata: Q11471 (https://www.wikidata.org/wiki/Q11471)
  • ISO 8601 timestamp: YYYY-MM-DDThh:mm:ssZ standard representation
  • IANA time zone: Region/City time zone database

Direct properties not applicable Not applicable

  • SI base unit: second s - defined by the caesium-133 hyperfine transition
  • leap seconds inserted since 1972: 27 seconds - as of 2026

Plane XCT: no invented physical properties.

Recognition optional Filled

  • Timestamps such as 2026-09-11T07:52:54Z
  • Durations such as PT3H or half-lives
  • Clock faces and displays
  • Not visible; shown by clocks, calendars and timestamps.

Capabilities and actions required Filled

  • measure it, with clocks referenced to atomic time
  • record instants, with timestamps and time zones
  • compute durations and intervals
  • schedule and coordinate, across zones

Hazards and failure modes required Filled

  • Time zone and daylight saving errors
  • Clock drift and unsynchronised systems
  • Leap second handling bugs
  • Mixing local and UTC timestamps

Standards and interfaces required Filled

  • SI definition of the second
  • ITU-R TF.460 on UTC
  • ISO 8601 and RFC 3339
  • National time zone law

Context of use required Filled

  • Ordering events, measuring durations, coordinating activity and scheduling.
  • instants and timestamps
  • durations and intervals
  • time scales: UTC, TAI, GPS
  • domain times: half-life, crystallisation time, paid time off

Sources Filled

  1. Wikidata item Q11471: time - identity and sense of the item
  2. Wikipedia: Time - general description of the item

Open questions

  • Should instants, durations and intervals be separate entries?
  • How should the registry require time zones on timestamps?
  • The registry entry has merged aliases such as paid time off; should they be split off?

Machine files

Card as JSON Specification Card backlog vercy.card/1

Provenance

thing registry research (pass 2) · unreviewed

Built from: models/things/publications/thing-q11471/spec.json