qualifier token a chosen word

identifier scheme

The namespace a trade identifier belongs to — GTIN-8/12/13/14, UPC, EAN, MPN, SKU, ASIN, ISBN, NSN, or item-group. A qualifier of `trade_identifier`: the value '0123456789012' is meaningless until the scheme says which registry it is read against. For the barcode family (GTIN/UPC/EAN/ISBN) the scheme is partly self-encoded in the code's length and prefix, but for MPN/SKU/ASIN/NSN it is NOT recoverable from the string, so the token is information-bearing — it is the only thing that tells an MPN from an SKU from an ASIN. A governed token (cardinality one per identifier statement) from a growing vocabulary (L13).

Identifier scheme is answered with one word chosen from the identifier schemes list — the same word shared across every product that uses it.

It is a qualifier of trade identifier — it has meaning only inside a trade identifier statement, one per statement, never on its own. It belongs with trade identifier to identity — who and what it is.

It is answered inside every trade identifier statement, not as a standalone question on a kind.

answered with: ◇token — a token — a word chosen from a fixed vocabulary, shared and filterable across products.
value domain: Identifier Schemes — the vocabulary its answers are drawn from.
qualifier of: trade identifier — one per statement — it has meaning only inside that host's statement.

Answered inside every trade identifier statement — not a standalone slot on any kind.