> For the complete documentation index, see [llms.txt](https://gl-docs.gitbook.io/zkpass/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr.md).

# DVR

- [High Level View](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/high-level-view.md): Data Verification Request (DVR) is the main zkPass module running within the framework of the zkPass Service.
- [Key Concepts](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/key-concepts.md)
- [User Data](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/key-concepts/user-data.md): User data encapsulates a spectrum of sensitive and confidential attributes, credentials, or claims, ranging from driver's licenses and passports to financial credentials such as bank account details.
- [DVR Info](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/key-concepts/dvr-info.md): Data Verification Request Info
- [zkPass Proof](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/key-concepts/zkpass-proof.md)
- [DVR Client Roles](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles.md): The DVR follows a robust trust model inspired by the W3C Decentralized Identifiers (DID) standards. Within the zkPass ecosystem, we define three client roles which participate in the zkPass ecosystem.
- [Data Issuer](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/data-issuer.md)
- [Providing User Data Retrieval API](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/data-issuer/providing-user-data-retrieval-api.md): Providing a REST API to retrieve the user data
- [Data Holder](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/data-holder.md)
- [1. Retrieving the DVR](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/data-holder/1.-retrieving-the-dvr.md): Retrieving the Data Verification Request (DVR) from the Proof Verifier
- [2. Retrieving the User Data](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/data-holder/2.-retrieving-the-user-data.md): Retrieving the User Data from the Data Issuer
- [3. Generating the Proof](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/data-holder/3.-generating-the-proof.md): Calling zkPass Service's generate\_zkpass\_proof REST API to create the ZkPass Proof
- [4. Verifying the Proof](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/data-holder/4.-verifying-the-proof.md): Sending the ZkpassProof object to the Proof Verifier for verification
- [Proof Verifier](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/proof-verifier.md)
- [1. Providing DVR Retrieval API](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/proof-verifier/1.-providing-dvr-retrieval-api.md): Providing a REST API to retrieve the DVR
- [2. Providing Proof Verification API](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-client-roles/proof-verifier/2.-providing-proof-verification-api.md): Providing a REST API to verify ZkPass Proof
- [DVR Query](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-query.md): DVR defines a JSON query language that allows the Proof Verifier to check if the user has data that meets specific requirements, conditions, or constraints.
- [Building Query Engine](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-query/building-query-engine.md)
- [Processing Query](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-query/processing-query.md)
- [Query Grammar](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-query/query-grammar.md)
- [Integration Guidelines](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/integration-guidelines.md): For successful integration into the DVR application workflow, each client stakeholder is advised to follow the guidelines specified in this documentation.
- [DVR Workflows](https://gl-docs.gitbook.io/zkpass/zkpass-developers-guide/zkpass-modules/dvr/dvr-workflows.md)