Represents an ad group bid modifier.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v26/resources/ad_group_bid_modifier.proto)

| Fields ||
|---|---|
| ## `ad_group` | `string` Immutable. The ad group to which this criterion belongs. |
| ## `base_ad_group` | `string` Output only. The base ad group from which this draft/trial adgroup bid modifier was created. If ad_group is a base ad group then this field will be equal to ad_group. If the ad group was created in the draft or trial and has no corresponding base ad group, then this field will be null. This field is readonly. |
| ## `bid_modifier` | `double` The modifier for the bid when the criterion matches. The modifier must be in the range: 0.1 - 10.0. Use 0 to opt out of a Device type. |
| ## `bid_modifier_source` | `https://developers.google.com/google-ads/api/reference/rpc/v26/BidModifierSourceEnum.BidModifierSource` Output only. Bid modifier source. |
| ## `criterion` Union field. The criterion of this ad group bid modifier. Required in create operations starting in V5. `criterion` can be only one of the following: ||
| ### `advance_booking_window` | `https://developers.google.com/google-ads/api/reference/rpc/v26/AdvanceBookingWindowInfo` Immutable. Criterion for the number of days prior to the start date of the booking. |
| ### `device` | `https://developers.google.com/google-ads/api/reference/rpc/v26/DeviceInfo` Immutable. A device criterion. |
| ### `length_of_booking` | `https://developers.google.com/google-ads/api/reference/rpc/v26/LengthOfBookingInfo` Immutable. Criterion for the length of the booking in days. |
| ### `start_date_range` | `https://developers.google.com/google-ads/api/reference/rpc/v26/StartDateRangeInfo` Immutable. Criterion for the date range of the start of the booking. |
| ### `start_day_of_week` | `https://developers.google.com/google-ads/api/reference/rpc/v26/StartDayOfWeekInfo` Immutable. Criterion for the day of the week of the booking start date. |
| ### `user_set_dates` | `https://developers.google.com/google-ads/api/reference/rpc/v26/UserSetDatesInfo` Immutable. Criterion for the date selection (default dates versus user selected). |
| ## `criterion_id` | `int64` Output only. The ID of the criterion to bid modify. This field is ignored for mutates. |
| ## `resource_name` | `string` Immutable. The resource name of the ad group bid modifier. Ad group bid modifier resource names have the form: `customers/{customer_id}/adGroupBidModifiers/{ad_group_id}~{criterion_id}` |