Represents a Retail Filter Tag.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v25/common/criteria.proto)

| Fields ||
|---|---|
| ## `expression_name` | `string` The name of the expression this tag belongs to. If empty, the tag is a top-level condition. |
| ## `value` | `string` The value of the tag. It can contain at most 50 characters. All Unicode characters except comma and newline are allowed. This field is required. |