# Audit trail

Zero Labs uses the following flow to make sure that there's a [**bi-directional link**](https://docs.zerolabs.green/zerolabs-tokenization-module/domain-definitions/bi-directional-link) between the REC Registry redemption statement and the minted Certificates (NFTs).

### Flow

![REC Registry user tokenizing their RECs (high-level flow)](https://1042227828-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FJ1hmZlUO8raciusperMH%2Fuploads%2FlihWsOnNDvBTaawu7bkP%2Fmermaid-diagram-20220509143753.png?alt=media\&token=fa294b17-b6aa-4d61-ae93-0d38285c4a8a)

### Sequence diagram

![](https://1042227828-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FJ1hmZlUO8raciusperMH%2Fuploads%2FK43Wmxm7NyUePskWkdob%2Fimage.png?alt=media\&token=4009c7d4-0d48-4fc2-b167-ced63bc32e3a)