Civil date and time sample contract

This specifies the conventional representation and established temporal meaning portion of the selected-sample operation, under ADR 0018: Civil date and time sample conventions. It applies after the selected effective data description, applicable format, conventional JSON value and decoded scalar text have been established. It does not select an alternative, acquire model data, infer a date from neighboring sample fields, or certify the whole model. RFC 9880 Appendix C.2 supplies abstract data meanings; RFC 3339 Section 5.6 names their conventional productions.

FullBaseline can establish the known date, date-time and time model interpretations without a supplied value. This M049 observation neither invokes the temporal evaluator nor consults leap-second knowledge. Actual constants and selected values still require their own established denotation under the rules below. An unavailable exceptional slot can leave constant meaning unfinished while the named model interpretation remains established.

Conventional values and calendar

Every numeric component uses ASCII digits and the displayed fixed widths. Source year is 0000..9999; month 01..12; day 01 through its Gregorian month limit; clock hour 00..23 and minute 00..59. February has 29 days when the year is divisible by 4, except a century not divisible by 400. The same rule applies to source year 0000, as the published RFC 3339 Section 2 and Appendix C arithmetic specifies. Gregorian arithmetic is used across the four-digit range without a historical local-calendar cutover. Offset subtraction may use an adjacent internal year outside that textual range; that intermediate result alone does not reject an otherwise permitted source date.

Seconds are 00..59 ordinarily, with 60 and a missing 59 governed below. A fraction is a dot followed by one or more ASCII digits. All digits remain exact; there is no fixed decimal scale, float conversion, nanosecond rounding or truncation. A long fraction may exhaust supported work, which gives undetermined rather than an invalid-format finding. Conventional source bytes and their JSON escape spelling remain retained separately from decoded text and temporal projection.

Z/z and signed offsets +HH:MM or -HH:MM are admitted, including both zero signs and offset hours through 23 with minutes through 59. The UTC coordinate is local clock minus offset, following RFC 3339 Section 4.2; a real-world timezone database is unnecessary. -00:00 denotes known UTC time while the local offset is unknown. Under the recorded RFC 3339 Section 4.3 baseline, Z/z and +00:00 carry the preferred-UTC-reference annotation. Preserve these annotations even though all three spellings use the same zero coordinate for leap-slot checking.

RFC 9557 Section 2 changes the Z annotation, while leaving UTC coordinate and this admission unchanged. That update is not implicitly adopted; a later deliberate baseline update must state it. Bracketed IXDTF timezone/calendar suffixes are not selected representations here. Neither an absent offset nor a timezone name supplies the RFC 3339 full-time offset. The date format has no offset suffix.

T/t is the selected date-time separator. The RFC 3339 note permits applications to choose another separator, so a space-separated timestamp fails this selected conventional representation without a claim that its abstract instant cannot exist or that every application forbids that syntax. ISO 8601 week dates, ordinal dates, expanded years, compact forms, comma fractions, hour 24, reduced precision and offset seconds are likewise outside these selected named productions. Malformed JSON, A002 duplicate-key refusal and unsupported escaped scalar decoding remain their existing input/context outcomes; temporal checking does not reclassify them as invalid dates. A supplied nonstring is not coerced. Null and conflicting effective type are evaluated under the existing nullable/type/choice contract rather than an unconditional nonstring format rejection.

The metadata quality modified has its own RFC 9880 Appendix A grammar allowing full-date or Z-terminated date-time, described by RFC 9880 Section 3.1. It does not make these sample formats UTC-only. A model metadata timestamp is not a default date or timezone for a sample.

Exceptional seconds and recorded knowledge

RFC 3339 Section 5.7 makes seconds conditional on leap adjustments and shifts the insertion point by the supplied offset. UTC 23:59 on the final UTC day of a month is the possible adjustment minute. June and December are historical and preferred opportunities, not a silently hardcoded universal sample grammar. Negative adjustments remove second 59; positive adjustments insert second 60. Fractions refer to the represented second and never roll it into the following minute.

For a date-time, derive the UTC minute and UTC date by subtracting the offset, including a change of day, month or year. The source date can be the following local day, such as 2017-01-01T05:44:60+05:45, whose leap slot is 2016-12-31 UTC.

Seconds 00..58 remain available independently of adjustment knowledge. A syntactic second greater than 60 rejects. An impossible insertion slot rejects even outside the recorded knowledge interval because the independent slot rule is established.

Initial deliberately recorded leap knowledge is IERS Bulletin C72, issued 2026-07-06, together with its Leap_Second.dat transition table and Bulletin C72 text. The inclusive knowledge interval is 1972-01-01 through 2026-12-31 UTC. Each listed +1 transition identifies an insertion on the preceding date; the initial 1972-01-01 offset is not an insertion event. No negative adjustment is recorded there. The bulletin explicitly establishes no insertion at the end of December 2026. The snapshot’s 2027-06-28 expiry is not a no-leap promise through that date. Before the interval and after it, needed adjustment facts remain unavailable. Processing never fetches a replacement implicitly. Record the snapshot’s byte identity in the standards knowledge basis; adopting new knowledge changes that basis deliberately, following ADR 0002: Recorded standards baseline.

The recorded knowledge identity is iers-bulletin-c72/2026-07-06. Snapshot SHA256 identities are 6cb6f5d4b819f2e568e25db4b0b26d89dedf031fdffb18bc94d40f4e94e268d7 for Leap_Second.dat and 310e172eadacacca3adf92cb9bd646fcc0d6320e35e996a106d2644ede3b52f0 for Bulletin C72. Its 27 positive insertion dates are:

1972-06-30  1972-12-31  1973-12-31  1974-12-31  1975-12-31
1976-12-31  1977-12-31  1978-12-31  1979-12-31  1981-06-30
1982-06-30  1983-06-30  1985-06-30  1987-12-31  1989-12-31
1990-12-31  1992-06-30  1993-06-30  1994-06-30  1995-12-31
1997-06-30  1998-12-31  2005-12-31  2008-12-31  2012-06-30
2015-06-30  2016-12-31

A date-free time has no UTC date by design. Ordinary seconds 00..59 are admitted as date-free clock coordinates without asserting occurrence on every calendar day. A possible inserted-second label 60 at UTC 23:59 is undetermined because its eligible leap-label interpretation is unestablished. This is not a missing required date field and does not establish invalidity. Second 60 at any other offset-adjusted UTC minute rejects. This is an explicitly selected conservative interpretation of RFC 3339 full-time as imported by SDF. An existential some-valid-date interpretation could admit eligible 60, but the RFC does not select that quantifier, so that alternative is deliberately deferred. The evaluator does not use a host date, a model metadata date or an unstated sample sibling. Date-free comparison, normalization modulo a day and recurring-schedule semantics are not established here.

Sample results, locations and finite work

The temporal obligation belongs to sample-abstract-values/1, keeping the immutable nine-area esdieff.sample/1 inventory. It is assessed when temporal admission or an independent representation/calendar/slot rejection is established. An unavailable needed interpretation or capability leaves that area undetermined. Applicable decoded JSON, scalar text length and patterns, const equality, nullable/type and alternatives keep their own areas. An established ordinary JSON string type does not complete abstract-values by itself. One complete admitting alternative can supply a witness; rejection still needs proof covering every potentially admitting alternative.

A rejected temporal form contributes an error in the sample domain with primary sample location and a related effective format constraint location, with source contributor locations when available. Its basis distinguishes selected representation convention from an established calendar/slot requirement and recorded leap knowledge. The space-convention condition must not assert an RFC-invalid abstract date-time. Undetermined leap or work contributes incompleteness with its reason and affected locations, not an invented rejection error. The versioned condition catalogue below preserves these distinctions.

For a supplied root JSON string, sample pointer is "" and its half-open span is the complete original JSON token, including quotes. Nested values use their actual sample pointer and original byte span. Effective location is the selected effective description’s applicable /format path; it is not a fabricated source location or byte span. Typed JSON inputs have a pointer and span:null unless genuine original bytes exist. Inherited or overridden format source locations are related explanations, not replacements for the sample identity. Presentation omissions preserve available identity/span and aggregate conclusions.

The implemented condition codes and bases are:

Each specialized incomplete condition identifies sample-abstract-values/1. It replaces the generic coverage detail for that same cause, including when optional detail is omitted. Independent const, alternative or other unavailable meanings retain their own details; each requested area is still counted once. Incomplete conditions never supply rejection witnesses or sample errors.

baseline.interpretations records ADR0018-selected-representation when the convention is consumed. baseline.temporal_knowledge carries the C72 identity, interval and both snapshot digests only after an actual adjustment query, including outside-interval queries and discarded branches. Dates, ordinary seconds 00..58, second 59 away from a boundary, date-free time and independently impossible insertion slots do not consult C72. Established null and wrong-kind constraints exclude temporal grammar and record neither use flag.

The evaluator precharges 2 * decoded_length + 256 original semantic-work units for the borrowed representation scan, bounded calendar/offset arithmetic and at most 27 recorded insertion comparisons. Both const operands and every potentially relevant branch use that same remaining request allowance. No additional temporal counter, refill, owned fraction or normalized temporal value exists. Metadata modified keeps its separate Z-only wrapper and existing precharge.

These projections assume exactly one effective full description with type:"string", nullable:false, one temporal format and no additional constraints. The four assessed areas are context, type/null, text/Boolean and abstract-values; the five remaining areas are established not applicable. The work-limit projection assumes only the temporal consumer’s budget is exhausted after the independent areas complete. They are expected contract observations, not executed product reports. A definite independent constraint rejection plus unavailable temporal meaning gives admission rejected, failed, complete false only when the unknown temporal meaning cannot change that proof. Strict warnings can fail disposition with admitted temporal/sample meaning. Detail truncation never changes admission, counters or aggregate errors.

All source, decoded text, parsed nodes, recursive alternatives, semantic work, location and report limits remain shared under ADR 0012: Exact numbers and JSON input policies, ADR 0013: Shared workflow and report guarantees and ADR 0016: Selected samples with explicit admission and coverage. Charge before scanning, copying or building exact fractions, offset projections and locations. Format capability is bounded independently of JSON source acquisition; raising one cap removes no other bound. No additional unbounded precision, live lookup, timezone database or calendar dependency is selected.

Representative observations and remaining scope

Under a common established civil format, null equals null and differs from an established nonnull civil value in either operand order. Malformed or uninterpreted nonnull values leave comparison undetermined. Null/null consults neither the nonnull representation convention nor leap knowledge; mixed pairs record only the nonnull interpretation and knowledge actually used. Null admission remains independent, including when nullable:false excludes it. Two nonnull dates with established Gregorian denotation compare by calendar date. The same date is equal and different dates differ, including day, month and year boundaries across the four-digit source range. The fixed-width convention permits validated decoded text to supply this comparison without a normalized retained value. JSON escape spelling does not matter; identical invalid dates do not establish equality and differing invalid dates do not establish a calendar disagreement.

Two nonnull date-times with established denotation compare by UTC instant under ADR 0018. Subtract the numeric offset with Gregorian day/year rollover, keeping UTC dates outside the source-year edges representable internally. Compare exact fractional digits after removing trailing zeros; absent and all-zero fractions are equal. An inserted second keeps its own slot, distinct from second 59 and the following day’s second 00. Offset annotations, letter case and JSON escapes do not distinguish instants. The RFC 3339 example 1996-12-19T16:39:57-08:00 equals 1996-12-20T00:39:57Z; .1 equals .100; an established Z value equals its +00:00 and -00:00 spellings. Invalid forms and absent needed adjustment knowledge prevent either an equality or a difference conclusion. Differing nonnull date-free time representations retain unavailable comparison meaning.

Temporal denotation alone does not establish sample admission when other constraints remain unfinished. ADR 0015: Bounded value equality in a resolved data context applies separately: invalid or unresolved strings do not denote a temporal value merely because their representations match. Gregorian-date and dated date-time equality supply constant checks, supported compound comparisons, uniqueness and declared-value consistency through that one contract. Actual date comparison records the selected convention without consulting leap knowledge; dated date-time comparison records only actual slot consultations. Model-only comparator capability uses no operands and records no representation consultation. Nonnull date-free time comparison beyond established identical representations, epoch conversion, ordering, duration arithmetic, physical clock correctness, recurring schedules and additional representations remain outside this scope.