# ParameterMutation

- [JSON representation](https://developers.google.com/analytics/devguides/config/admin/v1/rest/v1alpha/ParameterMutation#SCHEMA_REPRESENTATION)

Defines an event parameter to mutate.

| JSON representation |
|---|
| ``` { "parameter": string, "parameterValue": string } ``` |

| Fields ||
|---|---|
| `parameter` | `string` Required. The name of the parameter to mutate. This value must: \* be less than 40 characters. \* be unique across across all mutations within the rule \* consist only of letters, digits or _ (underscores) For event edit rules, the name may also be set to 'eventName' to modify the eventName in place. |
| `parameterValue` | `string` Required. The value mutation to perform. \* Must be less than 100 characters. \* To specify a constant value for the param, use the value's string. \* To copy value from another parameter, use syntax like "\[\[other_parameter\]\]" For more details, see this [help center article](https://support.google.com/analytics/answer/10085872#modify-an-event&zippy=%2Cin-this-article%2Cmodify-parameters). |