generated: '2026-07-21'
method: derived
source: https://docs.toucan.earth/developers/smart-contracts
standards:
  - id: erc-20
    conforms: true
    evidence: >-
      TCO2 tokens and carbon pool tokens (CHAR, NCT, BCT) are ERC-20 tokens with
      18 decimals; pool error codes reference ERC20 whitelisting/blacklisting
      (docs.toucan.earth/developers/smart-contracts, error codes 4/5/22).
  - id: erc-721
    conforms: true
    evidence: >-
      Retirement certificates are NFTs minted on retirement; batch NFTs are
      received by the batch contract (docs.toucan.earth/developers/smart-contracts/retirement-certificates,
      error code 43).
  - id: erc-1155
    conforms: true
    evidence: >-
      Pool error codes 57-60 describe ERC-1155 tokens scored and pooled
      (docs.toucan.earth/developers/support/error-codes).
  - id: graphql
    conforms: true
    evidence: >-
      Toucan Subgraphs expose GraphQL query endpoints via The Graph gateway on
      six networks (docs.toucan.earth/developers/subgraph).
  - id: thegraph-subgraph
    conforms: true
    evidence: >-
      Data surface is published as The Graph subgraphs with Studio API keys and
      explorer playgrounds (docs.toucan.earth/developers/subgraph).
  - id: oauth2
    conforms: false
    evidence: No OAuth2 surface documented; auth is Graph API key + EVM wallet signer.
  - id: rfc9457-problem-details
    conforms: false
    evidence: Errors are numeric smart-contract error codes, not HTTP problem details.