trade identifier
A trade/catalogue identifier carried by the product — its value is the identifying code itself (a free literal: a GTIN, a UPC, an MPN, an SKU, an ASIN, an ISBN, an NSN, an item-group id). Cardinality many: one product routinely carries several (a GTIN-13 AND a GTIN-14 for the case, a manufacturer MPN, a seller SKU). A self-correlating bundle: each identifier travels with its `identifier_scheme`, the namespace it is read against — the value and its scheme are one fact (a bare code is ambiguous between namespaces). This qualified host supersedes the earlier flat `gtin` literal, which could hold only a GTIN and could not name the scheme, so it could carry neither an MPN nor an SKU. The pool declares the bundle's grammar (a product HAS identifiers, each in some scheme); the actual codes are realised values stated downstream (L1).
Trade identifier is free text, written for one product alone and never shared as a category.
It belongs to identity — who and what it is.
the bundle what travels with each trade identifier
A trade identifier is not a lone value — each statement is a self-correlating bundle, carrying its own:
asked by the kinds that answer it
49 kinds answer it, each for any number of values. The same question can be reused by unrelated kinds — one meaning, many homes.
asked by kinds that answer it
The same question can be reused by unrelated kinds — one meaning, many homes.
| kind | how many |
|---|---|
| Product | many |