Follow-up to discussion in #4657 with @MatthiasWiesmann.

Problem Definition

While schema:serialNumber exists for string-based IDs, the Digital Product Passport (DPP) requires more complex identification mechanisms, specifically:

1. Decentralized Identifiers (DIDs): For verifiable credentials.
2. Resolvable Links: QR codes/NFC tags that point to a dynamic DPP endpoint.

A simple string is insufficient to capture the type and resolution method of these modern identifiers.

Proposal

Extend identifier to explicitly support complex PropertyValue objects for Web3/DPP contexts.

Example Usage

"identifier": [
{
"@type": "PropertyValue",
"propertyID": "did",
"value": "did:web:verisav.fr:product:12345",
"description": "Decentralized Identifier for Verifiable Credentials"
},
{
"@type": "PropertyValue",
"propertyID": "dppLink",
"value": "https://id.verisav.fr/12345",
"description": "Resolvable GS1 Digital Link"
}
]

text

This aligns with W3C DID specifications and GS1 Digital Link standards.