> For the complete documentation index, see [llms.txt](https://guardian.hedera.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guardian.hedera.com/docs/3.5.1/guardian/standard-registry/policies/policy-creation/introduction/global-events-reader-block.md).
# Global Events Reader Block
Subscribes to global topics and routes incoming events into policy branches.
* Can subscribe to multiple global topics.
* Reads/handles messages only from topics with Active = ON (OFF = ignore this topic).
* Lets you control subscriptions per topic/stream in the Reader UI:
* Active ON/OFF — ON = read/process, OFF = ignore.
* Hidden (optional) — stays in configuration but is hidden in UI.
* Routes an event into a branch only if validations pass:
* Document type matches branch configuration.
* If configured, the schema matches / validates for that branch.
* If applicable, field filters match.
* Applies filters only for VC, and only when Admin configured a schema for the branch.
## 1.1 Properties
| Property Name | Description | Example |
| --------------------------------------- | ----------------------------------------------------------------------- | ------------------------ |
| Default Active (in the block Meta Data) | controls the visibility in the runtime UI | Checked/Unchecked |
| Show Next button | enable to use this block inside a Step container. | Checked/Unchecked |
| Global topics | the list of default topicIds that Admin adds to the block configuration | 0.0.750.... |
| Active by default | controls the visibility of topicID | Checked/Unchecked |
| Branch event | output event name to trigger | branch 1 |
| Document type | expected type for this branch (VC / JSON / CSV / TEXT / ANY) | VC |
| Schema (optional) | local policy schema used for VC validation before routing. | Registrant & Participant |
* Events tab - setting output events to the branches.
## 1.2 API
* Uses the standard policy blocks API (setData), same as other blocks.
* Reader/Writer don’t introduce a new API — they only define their own payload format and supported operation values.
```
Reader payload (Update streams):
{
"operation": "Update",
"value": {
"streams": [
{
"globalTopicId": "0.0.7559767",
"active": true,
"branchDocumentTypeByBranch": { "branch 1": "vc", "branch 2": "vc" },
"filterFieldsByBranch": {}
}
]
}
}
```
---
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