Date and Time

Purpose

This standard defines the REQUIRED representation of date and time values exchanged across all integration boundaries.

The objective is to,

• Deterministic interpretation
• Cross-platform interoperability
• DST and timezone resilience
• Machine-governable validation
• Long-term scheduling correctness

Normative language (MUST, MUST NOT, SHOULD) follows RFC 2119 semantics.

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Classifications

There are two distinct semantic classifications of date-time representations.

Classification	Description	Deterministic at creation time
ABSOLUTE	Represents a past or present instant in time	Yes
SCHEDULED	Represents a future planned occurrence	No (offset subject to change)

Representation strategy depends on the applicable classification.

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Rules

ABSOLUTE Timestamp Standard

Rules

All ABSOLUTE timestamps MUST,

1. Conform to RFC 3339
2. Be expressed in UTC
3. Use the literal Z suffix
4. NOT use Unix Epoch format
5. NOT use timezone offsets (+01:00)
6. Represent a single unambiguous instant

Canonical Format

YYYY-MM-DDTHH:mm:ssZ

Optionally, fractional seconds MAY be allowed, with a maximum of 9 fractional digits.

YYYY-MM-DDTHH:mm:ss.SSSZ

Validation Regex

^d{4}-d{2}-d{2}Td{2}:d{2}:d{2}(.d{1,9})?Z$

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SCHEDULED (Future) Timestamp Standard

Distinction

Future timestamps are not deterministic because,

• DST (Daylight Saving Time) rules may change
• Jurisdictions may modify timezone legislation
• Offsets are derived values
• Offset alone does not uniquely identify a timezone

→ Offsets MUST NOT be authoritative for future scheduled timestamps.

Rules

If a date-time represents a SCHEDULED future event,

• An IANA (Internet Assigned Numbers Authority) timezone identifier (ZoneId) is MANDATORY
• Zone MUST take precedence over offset
• Offset-only representations MUST be rejected

Canonical Formats

Timezone-Aware Systems (Preferred)

Use RFC-9557 format

YYYY-MM-DDTHH:mm:ss[Area/Location]

This preserves timezone identity independent of offset.

Timezone-Unaware Systems (Fallback)

Use the Triple-Field Model

• local_timestamp: LocalDateTime without offset
• zone: Valid IANA ZoneId
• utc_timestamp: RFC-3339 canonical UTC

Here, the authoritative representation is (local_timestamp, zone), while utc_timestamp is a derived projection.

Interpretation Algorithm

To compute execution instant,

• Read zone
• Apply current tzdb (Timezone DB) rules
• Derive offset
• Compute utc_timestamp
• Execute at derived instant

NEVER reverse this order.

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Examples

ABSOLUTE Timestamps

Valid

{ "created_at": "2026-02-16T09:30:45Z" }

{ "created_at": "2026-02-16T09:30:45.123Z" }

Invalid

{ "created_at": "1698393600" }

{ "created_at": "2026-02-16T10:30:45+01:00" }

SCHEDULED Timestamps

Valid

{ "scheduled_at": "2027-12-01T11:00:00[America/New_York]" }

{
  "local_timestamp": "2027-12-01T11:00:00",
  "zone": "America/New_York",
  "utc_timestamp": "2027-12-01T16:00:00Z"
}

Invalid

{ "scheduled_at": "2027-12-01T11:00:00Z" }

{ "scheduled_at": "2026-02-16T10:30:45+01:00" }

{ "scheduled_at": "1698393600" }

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Enforcement Rules

The following payloads MUST be rejected,

For ABSOLUTE timestamps:

• Unix Epoch format
• Offset-based timestamps
• Missing timezone indicator
• Local timestamps without Z

For SCHEDULED timestamps:

• Missing zone
• Invalid IANA (Internet Assigned Numbers Authority) ZoneId
• Offset-only representation
• UTC timestamp inconsistent with tzdb projection

Validation MUST occur at contract boundary.

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Rationale

This standard ensures,

• Deterministic event replay (event-driven systems)
• Cross-language interoperability
• Protection against DST drift
• Regulatory resilience
• AI-governable timestamp validation
• Future-proof scheduling semantics

UTC guarantees stability for ABSOLUTE time.

Zone-based representation guarantees correctness for SCHEDULED time.

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References

• ISO-8601 (Date)
• RFC-3339 ((Z Form))
• RFC-9557
• TZDB
  • Current TZDB Explorer, with historic versions

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Version History

Version	Date	Change
2.0.0	2026-02-16	Introduced scheduled timestamp model
1.1.0	2026-02-16	Added fractional seconds
1.0.0	2023-10-27	Initial definition