> ## Documentation Index
> Fetch the complete documentation index at: https://docs-xcor.paloaltonetworks.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Change event limits

> Reference the ingest rate, request size, and field limits that apply when creating change events with the CreateEvent API.

In addition to using Palo Alto Networks Cortex XCOR, you can use the
[CreateEvent API](/tooling/api-info/data_definition/operations/CreateEvent)
to create change events. This API can ingest 300 change events per minute, per block
in a single tenant. The total request size must be less than 1 MB.

## Change event fields

The CreateEvent API accepts the following fields with the stated limits:

| Field | Description | Required | Validation | Configurable | Failure |
| - | - | - | - | - | - |
| `title` | Brief description of the change event. | Yes | Maximum of 100 characters. | No | Error |
| `source` | Identifies where the data originated. | Yes | Maximum of 50 characters. | No | Error |
| `category` | Informs Cortex XCOR about the kind of change event. | Yes | Must be one of:<br />`"alerts"`<br />`"broadcasts"`<br />`"chronosphere"`<br />`"deploys"`<br />`"feature_flags"`<br />`"infrastructure"`<br />`"third_party"` | Yes | Error |
| `happened_at` | Indicates when the change event occurred, which defaults to `now` if unset. | No | Must be a Unix epoch timestamp.<br /><br />Can be set only to 24 hours before or after the current time. | Yes, with a restart | Error |
| `type` | Differentiates change events within a particular `category` or `source`. | Yes | Maximum of 50 characters. | No | Error |
| `labels` | Key values associated with a change event. | No | Maximum of 200 labels (key-value pairs) per event.<br /><br /> - Keys: Maximum of 500 characters.<br /> - Values: Maximum of 5,000 characters. | No | Error |
| `payload_json` | Payload associated with a change event. | No | Maximum of 100,000 characters. | No | - |
| `payload_object` | Payload associated with a change event, if the original event was in key-value format. | No | Maximum of 100,000 characters. | No | - |


## Related topics

- [Use change events](/observe/enable-events/use-events.md)
- [Enable change events on dashboards](/observe/enable-events/dashboards.md)
- [Change events](/overview/concepts/change-events.md)
- [Monitor details](/investigate/alerts/monitors/monitor-details.md)
- [Enable change events on traces](/observe/enable-events/traces.md)


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