> [!CAUTION]
> **Caution:** This documentation is for Google Ads API **v24** . The latest active version is [**v26**](https://developers.google.com/google-ads/api/reference/rpc/latest/CustomVariable).

A custom variable.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v24/services/conversion_upload_service.proto)

| Fields ||
|---|---|
| ## `conversion_custom_variable` | `string` Resource name of the custom variable associated with this conversion. Note: Although this resource name consists of a customer id and a conversion custom variable id, validation will ignore the customer id and use the conversion custom variable id as the sole identifier of the conversion custom variable. |
| ## `value` | `string` The value string of this custom variable. The value of the custom variable should not contain private customer data, such as email addresses or phone numbers. |