Changelog

Spec-level changes, following the SemVer policy. Patch and minor releases are backward-compatible: existing packets stay valid.

The schema is currently frozen against breaking changes for the public comment period (2026-06-23 → 2026-07-23) and the 6-month stability window ahead of IANA registration.

3.0 — current

The baseline v3.0 specification: the five-layer model (A–E), L1/L2/L3 conformance, GRADE-aligned evidence_grade, the never-collapsed clinical_status, per-record licensing (license_label + rights_url), and the _extensions escape hatch.

Additive optional fields (backward-compatible)

Added since the initial 3.0 cut — all optional, so every existing packet remains valid:

• Source.claims[] — claim-level evidence grading (each claim carries its own grade/status).
• Source.temporal_validity — first-class staleness windows (valid_as_of, valid_until, review_due, supersede links).
• Source.quality_dimensions — methodology scoring alongside the GRADE letter (risk of bias, replication status, …).
• Provenance.derived_from[] — structured, CID-anchored lineage edges to upstream packets.
• Cid definition — content identifiers (sha256-<hex>) over the JCS-canonical form.

Compatibility guarantees

Change class	Example	Compatibility
Patch	clarify normative text, fix an example	always
Minor	new optional field, new enum value, new x- classification	always (consumers must tolerate unknown fields)
Major	remove/rename a field, structural change	breaking — migration guide + 12-month maintenance window

See Governance for the full policy and the path to IANA/W3C.

→ Related: Governance · Call for Comments