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ADR 0022 — Data licensing: a rights IRI on the annotation, a default license in the well-known

• Status: accepted
• Date: 2026-07-05

Context

The requirement is as old as the project. The original 2014 Freedback whitebook ("Data Distribution Policies") demanded that every piece of feedback carry explicit licensing, recommended Open Data / permissive Creative Commons defaults, and asked that licensing information be exposed at a designated endpoint so it is "contractually valuable for both collectors and publishers". The modern protocol had no licensing story at all: collectors aggregating annotations across servers had no machine-readable terms to rely on, and publishers had no way to state any.

Two constraints shape the solution:

1. Zero net-new vocabulary if the standards already provide it (the spirit of INVARIANT 2). The W3C Web Annotation model already defines a rights property on annotations — an IRI identifying the license — mapped to dcterms:rights in the anno @context we pin.
2. A license is a statement by the author. Under the content-addressing scheme (ADR 0002) and detached signatures (ADR 0003), anything that changes the meaning of an annotation must live inside its canonical bytes; anything appended by intermediaries must not.

Decision

1. Adopt the W3C rights property — no new vocabulary. The model gains an optional rights: Option<String> (a license IRI, e.g. https://creativecommons.org/licenses/by/4.0/). The pinned Freedback @context gains the matching rights → dcterms:rights (@type: @id) term — an additive context change, allowed by the stable-URL policy. Both ingest paths (the alias normalizer, ADR 0007, and full JSON-LD compaction, ADR 0011) preserve it.
2. rights is content. When present it participates in the RFC 8785 canonical bytes: the same feedback under a different license is a different statement (different dedup id), and the author's signature covers the license. When absent, the canonical bytes are byte-identical to the pre-licensing form (skip_serializing_if), so every existing fixture, signature, and dedup id remains valid — pinned by test.
3. Validation stays in SHACL (INVARIANT 3): dcterms:rights is optional, sh:maxCount 1, sh:nodeKind sh:IRI. A pure relaxation of the profile — no previously-valid data becomes invalid — so the published shapes.ttl stays stable-URL-compatible.
4. A server-level default license at the designated endpoint. The feedback server takes FREEDBACK_DEFAULT_LICENSE (an IRI) and, when set, surfaces it in /.well-known/freedback as "license". Semantics: annotations served without an explicit rights are distributed under the server's default license; an annotation's own rights always takes precedence. The server never stamps the default into stored annotations (that would forge content into signed bytes) and enforces nothing beyond the SHACL IRI check — the protocol carries the terms; contract law does the rest.
5. Every writer can set it. freedback write --license <IRI> (CLI) and a data-license attribute on every widget kind (signed and bearer paths — in the signed path the license is part of the signed content).

Why not the alternatives

• Per-server-only licensing (no per-annotation field). Simple, but the license would change when an annotation federates through a differently- configured cache, and authors could not choose terms at all. The author owns the annotation (INVARIANT 4); the license is theirs to state.
• A mandatory rights field. Faithful to the whitebook's letter, but too much friction: every existing annotation, fixture, and signing client would break (a required field changes every canonical byte stream), and casual feedback would need a licensing decision up front. The server default covers the common case; the field covers the explicit one.
• License in the body. The body is the feedback itself (INVARIANT 2); licensing is metadata about the whole annotation. The envelope already has a standard slot for it.

Consequences

• Annotation gains rights + with_rights; canonical-bytes tests pin both directions (absence unchanged, presence changes the id). The widget JCS cross-language pin gains a licensed variant.
• The RDF mapping emits dcterms:rights as an IRI node (non-IRI values become literals that fail the SHACL node-kind check → 422), and the SHACL-subset interpreter learns sh:nodeKind.
• /.well-known/freedback may carry "license"; discovery/collection tooling can read a server's terms before harvesting. Aggregators that mix servers should track the per-annotation rights (or the origin server's default) if they need to honor per-item terms — future work if it ever matters.
• Deletion is unaffected: erasure (ADR 0021) removes the record regardless of its license — the right to be forgotten is not waived by licensing.