# Expiry, Revocation and Updates Velocity protocols and underlying tech enable Issuers to revoke and to update issued credentials. Revoking credentials simply requires sending the credential ID to the revocation service. This will save an entry to the revocation ledger. Revocation registries are stored on the Velocity decentralized trust ledger (blockchain), enhancing its security and availability. Wallet services are notified to trigger push notifications, a private message, or an email to the holder to notify them that the issuer has revoked the credential. Updating a credential is also supported by revoking and reissuing the credential with the updated information all while maintaining the new credential linked to the previous one. Again, the holder is notified that the issuer has updated the credential. When applicable, credentials schemas require the issuer to add expiry date to the credential when issued to the holder. Expiry date is checked and verified as part of the protocol of multi-dimensional credential checks implemented by relying party agents. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://velocity-network.gitbook.io/velocity-network/implementing-proof-of-qualifications-at-scale/expiry-revocation-and-updates.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.