Registry Record Creation
How verified MassIDs become tamper-evident, publicly verifiable registry records — from metadata creation through durable public storage to issuance on the public registry.
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From verified data to public registry records
A MassID that has passed methodology verification can be issued as a registry record: a tamper-evident, publicly verifiable entry on the public registry. A MassID is recorded there before any certificate issued from it is. Issuance creates a publicly verifiable link between the physical recycling work and its digital representation in the registry.
Registry issuance is the bridge between the digital MRV (dMRV) verification process and the credit lifecycle that ultimately produces tradeable environmental credits.
The registry-record creation process
1. Verification complete
The MassID has passed all methodology checks. Its material type, weight, and chain of custody are validated, and all compliance conditions defined by the applicable methodology are satisfied.
2. Metadata creation
Structured metadata is compiled for the MassID. This metadata captures the complete provenance record:
| Field | Description |
|---|---|
| Material type | The waste material classification (e.g., clear glass, plastic, organic food waste) |
| Weight | The verified weight in kilograms |
| Chain of custody | Every participant who handled the material, identified by a non-reversible participant hash and role |
| Timestamps | When each event in the chain of custody occurred |
This metadata becomes the content-addressed description referenced by the MassID's registry record. When a certificate issued from this MassID is recorded on the public registry, its metadata carries the methodology that verified the material — its name, version, and a link to the published specification — and references the MassID by token id and IPFS URI. It also links to a public audit report on IPFS that lists each rule executed and its result, and that report links to the methodology. The Carrot Registry shows the MassID audit rule by rule.
3. Decentralized storage
The compiled metadata is uploaded to IPFS (InterPlanetary File System), producing a content-addressed URI. This URI is unique to the metadata content — any change to the data would produce a different URI, making the stored record tamper-evident.
The IPFS URI is then referenced by the on-chain registry record, linking the lightweight blockchain entry to the full metadata stored in decentralized storage.
4. Registry record creation
The MassID is recorded on-chain as a non-transferable registry record held by the Vault contract. The implementation uses ERC-721, while the public model is the MassID record itself. The creation transaction records the IPFS metadata URI on-chain, associating the registry entry with its provenance data. Because the metadata is content-addressed, that association is tamper-evident: any later change to the on-chain reference emits a public event, so the record is auditable rather than silently editable.
A registry record can also be revoked. A network operator can revoke a MassID when its underlying data is later found to be invalid, which replaces its metadata reference with a revocation record and removes the token from the Vault. Revocation is blocked once credits from the MassID's certificates have been sold, and it does not cascade — the linked certificates have to be revoked first.
Because MassID records are non-transferable, they cannot be traded or moved between accounts. This ensures the provenance chain remains intact and prevents speculative activity on verification records.
5. Record linking
The recorded MassID is linked to its entry on the public registry, so the blockchain and the Carrot Registry reference the same record — a consistent, auditable trail across both.
What happens next
Recorded MassIDs are the foundation upon which the rest of the credit lifecycle is built. Once a MassID exists on the public registry:
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Certificates can be recorded — A certificate (RecycledID or GasID) issued from the MassID, after it passed methodology verification at a facility accredited by independent third-party auditors, is already published in the Carrot Registry. It can now be recorded on the public registry, referencing the underlying MassID record as proof of the physical work performed. Carrot records certificates as inventory is needed, not all at once.
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Credits are issued — Recording a certificate issues its fungible credits (TRC or TCC) in the same transaction, using the unit defined by its methodology. These credits are the tradeable units that buyers purchase to meet their environmental commitments; a certificate that has not been recorded has no issued credits.
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Full traceability is established — From a retired credit, any party can trace back through the certificate, to the recorded MassID, to the IPFS metadata, and ultimately to the specific waste batches and supply chain participants that performed the work. This traceability is publicly verifiable through the Carrot Registry or any blockchain block explorer (e.g. PolygonScan).
Related pages
- Credit Lifecycle — The MassID, Certificate, and Credit lifecycle and relationships
- Smart Contracts — The on-chain infrastructure that manages registry-record creation and custody
- MassIDs — The foundational data unit representing verified waste batches