period
Enable an agent to recognise a period as a temporal extent, assess how its boundaries are established, and determine which temporal comparisons or operations are justified.
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.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise a period as a temporal extent, assess how its boundaries are established, and determine which temporal comparisons or operations are justified.
A period is an extent of time delimited by boundaries or distinguished by a recurring process, characteristic conditions, or an adopted convention.
It can be Resolve a period name or relative expression into attributed candidate boundaries.; Determine whether a dated observation falls inside, outside or ambiguously near a boundary.; Calculate a duration or duration range when the boundary evidence and reference system permit it.; Compare periods for overlap, containment and succession with explicit uncertainty.; Partition or aggregate periods while recording gaps, overlaps and endpoint conventions.; Associate an occurrence with a recurring series without assuming exact repetition..
Distinguishing features
A period has temporal extent; an instant identifies a temporal position without extent at the adopted resolution.
A located period can have a duration, but a duration alone does not identify when that period occurs.
An event may establish a period's boundary or occupy it; the period itself does not specify what happened.
A period need not recur; recurrence requires a separate rule connecting multiple occurrences.
A rotation period additionally requires a rotating system and a criterion for completing a rotation.
Scope
+ Temporal extent and the rule that identifies a particular period
+ Start and end boundaries, including uncertain, open and disputed boundaries
+ Duration, temporal resolution and the reference system used to express them
+ Named or conventional periodisation and its attribution
+ Containment, overlap, succession and membership in a recurring series
- Events and processes occurring during a period, beyond their role in identifying its boundaries
- Rotation period as a specialised measure tied to a rotating system
- Calendars, clocks and time scales as systems in their own right
- Historical participants, causes and consequences beyond claims needed to delimit a period
- Non-temporal senses of period, including punctuation and mathematical structures
Characteristics
- Identification basis
- explicit endpoints | named convention | boundary events | relative rule | recurrence rule | unresolved Determines what evidence is needed to recognise the same period across descriptions.
- Temporal reference system
- Applicable calendar, time scale, time zone or relative temporal origin Makes boundary expressions interpretable and determines whether comparisons require conversion.
- Boundary expressions
- Start and end positions, boundary events or rules, with inclusion conventions Establishes which temporal positions belong to the period.
- Boundary certainty
- For each boundary: exact at stated resolution | approximate | disputed | unknown | explicitly unbounded Prevents missing information from being treated as a definite boundary or an absence of limits.
- Duration
- Value or range in stated elapsed-time units, or calendar-relative amount with calculation convention Supports length comparisons without assuming that calendar units always have fixed elapsed lengths.
- Temporal resolution
- Smallest supported temporal distinction, such as second, day, year or an explicitly described interval Limits the precision of boundary placement and derived comparisons.
- Temporal relationships
- before | after | meets | overlaps | contains | during | coextensive, relative to another temporal extent Allows an agent to position the period among other periods while preserving uncertainty.
- Recurrence membership
- No recurrence asserted, or link to a series with occurrence identifier and recurrence rule Separates one occurrence from the pattern that generates or groups occurrences.
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.period-communication
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 5 bundles · 9 layers · 17 findings · 25 questions.
Period identity What makes this temporal extent a distinct period and what its label denotes.
The word period can designate a located interval, a named temporal grouping or a recurring occurrence; agents must establish the intended referent before operating on it.
Temporal referent
Distinguish the period from its length, its contents and its recurrence pattern.
Referent test
Establish whether the expression identifies a temporal extent rather than merely a quantity of time or an event.
- Does this expression identify when an extent occurs, how long it lasts, or a rule for producing occurrences? definition
- Which properties identify this period independently of the events taking place within it? definition
Naming and convention
Connect named periods to the practices or authorities that define their temporal reach.
Name resolution
Treat shared names as potentially ambiguous until their convention and context are known.
- Which source or community defines the temporal extent associated with this name? provenance
- Do different uses of this name designate the same extent, overlapping extents or separate occurrences? boundary
Temporal boundaries How the period begins and ends, and how confidently those limits can be placed.
Membership and temporal comparisons depend on boundaries that may be conventional, event-defined, incomplete or disputed.
Boundary rules
Specify endpoint expressions and the conditions under which they delimit the period.
Endpoint definition
Identify the start and end separately, including whether an endpoint belongs to the period.
- Which dates, events or rules establish the start and end of this period? boundary
- Are the endpoints included, excluded or left unspecified, and how are observations exactly at a boundary treated? boundary
Boundary uncertainty
Preserve missing, approximate and competing boundary claims without collapsing them into one asserted interval.
Alternative delimitations
Separate disagreement about a boundary from uncertainty within a single account.
- For each endpoint, is the limit unknown, explicitly absent, approximate or disputed between sources? boundary
- Which evidence supports each candidate delimitation, and does it concern the same interpretation of the period? provenance
Temporal measurement Express and measure the period using an explicit temporal frame and supported precision.
Dates and lengths cannot be compared reliably when their reference systems, calendar conventions or precision differ.
Reference frame
Identify the temporal coordinates needed to interpret boundary expressions.
Coordinate interpretation
Make absolute and relative boundary expressions comparable only through justified mappings.
- Which calendar, time scale, time zone or relative origin is required to interpret each boundary? measurement
- Can the boundaries be expressed in a common reference system without introducing unsupported precision or resolving an ambiguity by assumption? action
Length and resolution
Distinguish elapsed duration from calendar counting and constrain results to the available evidence.
Duration derivation
Derive the period's length using stated units, endpoint assumptions and uncertainty.
- Is the requested length elapsed time, a calendar-relative amount or a count of included calendar units? measurement
- What value, range or bound on duration is justified by the endpoint uncertainty and temporal resolution? measurement
Temporal composition Relate the period to other extents, observations and recurring occurrences.
Agents use periods to organise time; valid grouping and comparison require explicit membership, continuity and recurrence rules.
Membership and partition
Assess containment and the effects of splitting or joining temporal extents.
Interval operations
Determine which interval relationships and transformations the boundary evidence supports.
- Is a given observation or subperiod definitely inside, definitely outside or only possibly within this period? boundary
- When splitting or joining these periods, do the boundary conventions produce gaps, overlaps or a continuous extent? action
Recurring occurrences
Connect individual periods to a series without confusing occurrence identity with cycle length.
Recurrence rule
Establish whether recurrence is asserted and which rule distinguishes successive occurrences.
- What rule and temporal anchor identify successive occurrences, and are their lengths fixed, calendar-dependent or variable? definition
- What evidence permits an agent to infer a later occurrence, and how should exceptions or interrupted recurrence be represented? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- The temporal sense is inferred from domain XCT.TME; the registry supplies no definition to distinguish a general interval from a cycle period.
- Geological period is a formal rank, whereas historical period boundaries may depend on interpretation.
- This is recall-based information; no sources were consulted.
- Which of these check these first hold for the sense of period this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Calendar period
- Historical period
- Geological period
- Reporting or accounting period
- Period of a recurring process
- Which of these kinds and varieties hold for the sense of period this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- ISO 8601 time-interval representation - start/end or start/duration - Represents temporal extent; it is not a unique identifier for a named period.
- Which of these identifiers and schemes hold for the sense of period this model covers, and on what evidence? provenance
Standards and regulation
Recalled without web access and unsourced; every item is a lead to verify.
- ISO 8601, issued by the International Organization for Standardization, specifies representations of dates, times, durations and time intervals.
- The International Chronostratigraphic Chart, maintained by the International Commission on Stratigraphy, provides the standard framework for named geological periods and their boundaries.
- Which of these standards and regulation hold for the sense of period this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Grouping historical evidence into periods with shared characteristics
- Defining reporting, accounting and statistical observation windows
- Scheduling activities within calendar intervals
- Expressing the time required for one cycle of a recurring process
- Organizing geological time
- Which of these real-world use hold for the sense of period this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Duration - No universal range; depends on the boundaries and application. - second or an explicitly specified calendar unit
- Cycle period - Positive; for a periodic process, T = 1/f. - second
- Which of these typical measurements hold for the sense of period this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Confusing a situated interval with its duration
- Treating disputed or approximate boundaries as exact
- Assuming calendar months or years have a fixed duration in seconds
- Leaving endpoint inclusion unspecified, causing gaps or double counting
- Using a single cycle period for a process whose recurrence varies
- Which of these failure modes and hazards hold for the sense of period this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Calendars and fiscal-year conventions produce different period boundaries.
- Historical period names and boundaries vary between regions and scholarly traditions.
- Local time zones and daylight-saving rules can change the elapsed duration of calendar-based periods.
- Which of these regional variation hold for the sense of period this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- time interval - A time interval emphasizes temporal boundaries; period can additionally denote a named historical division or a cycle duration.
- duration - Duration measures temporal extent without necessarily locating it on a timeline.
- instant - An instant is a temporal position without extent.
- frequency - Frequency counts cycles per unit time; period measures time per cycle.
- rotation period - A rotation period specifically measures one complete rotation relative to a stated reference frame.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of period this model covers, and on what evidence? provenance
What the second pass must settle
- Does registry id vr.tr.period-q392928 denote a general temporal extent, a recurrence duration or a narrower sense of period?
- Must every period be continuous, or does the registry admit named periods composed of separated intervals?
- Should explicitly unbounded extents and zero-duration limits count as periods, or belong to neighbouring temporal concepts?
- When competing conventions assign different boundaries to one named period, should they be interpretations of one referent or distinct registered periods?
- How should the general period model relate to rotation period so that cycle-specific measurements are owned by the specialised model?