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How do we specify in the verifiable credential the trusted registry where the proofs are registered?
How do we stablish establish a standard for both centralized and decentralized registries to store and make available the proofs in a way that is common to everyone, so once the verifier figures out the trusted ledger to be checked and the access point to it (which should be able to do directly from the credential), the protocol to accomplish verification is standardized
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