02 — Identity and properties

Document status: draft. Canonical source.

Entity identity

Every authored entity MUST have a stable 128-bit-or-greater identifier. Identity MUST NOT depend on name, path, child index, geometry or serialized byte offset. Implementations MAY use UUIDv7/UUIDv4-compatible identifiers; the normative requirement is uniqueness and stability, not one generation algorithm.

Immutable assets MAY additionally use cryptographic content IDs.

Property model

A property is addressed by (entity_id, namespace, key). Core properties use the nuif namespace. Published extensions use registered namespaces and vendor extensions use registered vendor identifiers.

Properties distinguish:

• authored value;
• token/expression binding when present;
• resolved value for an evaluation context;
• provenance/correspondence metadata.

Resolved values MUST NOT overwrite authored values.