Chain of Custody Models

[harleytrustprovenance]

This PR introduces a new document titled "Chain of Custody," which has been renamed from "Mass Balance" to avoid confusion, as "Mass Balance" refers specifically to one of the four chain of custody models.

Work Produced:

• Identification of the four chain of custody models:
  • Identity Preserved
  • Segregated
  • Mass Balance
  • Book and Claim
• Documentation of the evidence required for each chain of custody model.
• Explanation of the role of third-party attestations in supporting these models.
• Outline of a potential methodology for the "Book and Claim" model.

[nissimsan]

This is excellent, @harleyjackthomas. Can't wait for this to get mode concrete and implementation-focused.

Don't be shy to push ahead with a merge. Something is much better than nothing.

[onthebreeze]

Hi Harley. This is great work. I'm approving this PR for draft release so that we have a published baseline to talk about. Some observations.

• The idea of a third party attestation of mass balance or other chain of custody model (except book & claim) is on the mark. I agree it's the only practical way to manage confidentiality and achieve some confidence.
• I think that references to schema in your code snippets are too coarse - probably should be more like criteria and related regulation or standard - similar to the existing assessment model in the DCC.
• we might need to extend this model to cover a standard for the confidential information exchanged between member and auditor as well as the standard for the more public attestations issued by the auditor.
• an entity like an industry association doing the chain of custody accounting as a service for their members seems like a great business pattern that is worth a mention - because each member has a trusted relationship with their peak body and every member wants the peak body to keep the other members honest.
• A good discovery pattern might be to link the chain-of-custody attestations to the identified facility, grouped by product class produced by the facility, and discoverable as an IDR linkset from the facility ID?

[harleytrustprovenance]

Thank you for the positive feedback @onthebreeze , is the appropriate workflow here to get this feedback documented as issues for the group to collectively tackle?

[onthebreeze]

Yes, why dont you create a few issues, reference them here, then we'll merge this PR ;)

[peirens-bart]

Hi Harley. I do have some question:

• What happens to the sold credits if the certifier is no longer there, can other certifiers take over credits?
• How then do we get proof of retired credit if the selling certifier is no longer there?
• Can credits be purchased from a certifier that falls under different legislation?

[harleytrustprovenance]

@peirens-bart I don't have a concrete answer to those questions, I believe this is an issue that isn't concretely defined or solved yet. @onthebreeze is this getting into durable storage, when I believe it mentioned briefly in the DAC docs?

[harleytrustprovenance]

Thank you everyone for the feedback and questions, I have documented the above in various issues:

• Chain of Custody: Improve Schema References in Code Snippets #257
• Chain of Custody: Extend Model to Cover Confidential Information Exchange Standards #258
• Chain of Custody: Add Consideration for Industry Associations as Chain of Custody Service Providers #259
• Chain of Custody: Improve Chain of Custody Discovery via Facility & Product Class IDR Linkset #260
• Chain of Custody: Durable storage of credits / retired credits #261

[onthebreeze]

Merging this PR to re-baseline this excellent discussion - recognising that Harley has created five issues to reflect team feedback to date.