Common Media Client Data: Custom Keys Registry

Registry version: 1.0.0

A shared, informal registry of custom keys for the CMCDv2 specification (CTA-5004-A). If you’re using CMCD in any player environment and want to use additional information in a well-defined manner, this repo gives you a consistent naming scheme and a curated list of keys you can use and contribute to.

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What’s in here

• A clear key schema – How to name custom keys (short, abbreviated names to keep payloads small), what characters are allowed, and how they map to CMCD headers. Everything is documented in docs/key-schema.md.
• A curated registry – A list of registered keys with descriptions, value types, and examples. You can browse it in a human-friendly table or consume it as JSON for tooling.
• A simple contribution process – Propose a new key via a GitHub issue; after review, maintainers add it to the registry so others can use it too.

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Quick start

Just want to see what keys exist?
Open keys/README.md for a readable table of all registered keys, with examples in CMCD format.

Need the data in code or automation?
Use keys/registry.json: same list, machine-readable.

Building with the Common Media Library?
We have a small integration example showing how to send these custom keys with @svta/common-media-library (CML).

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Proposing a new key

Have an idea for a key that would help the community? Open a GitHub issue using the “Propose a custom key” template. Describe the key, its purpose, and an example value. After review, accepted keys are added to the registry. The full process and rules are in CONTRIBUTING.md.

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Reference and tooling

• CMCDv1 specification (CTA-5004) – Common Media Client Data specification (version 1).
• CMCDv2 specification (CTA-5004-A) – Common Media Client Data specification (version 2).
• CTA-WAVE (discussion / feedback) – Where the spec is discussed and evolved.
• Common Media Library – GitHub · npm
• Registry (JSON): keys/registry.json
• Registry (generated table): keys/README.md. Run node scripts/generate-keys-readme.js from the repo root to regenerate after editing the JSON.
• Schema: schemas/registry.schema.json, for validation.
• Key format and rules: docs/key-schema.md and CONTRIBUTING.md.

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License

MIT. See LICENSE.