The reach plan buying method for an ad product.

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

| Enums ||
|---|---|
| ## `AUCTION` | Bidding on ads with a target CPM. |
| ## `RESERVATION` | Buying method that encompasses deal-based and instant reserve pricing. |
| ## `UNKNOWN` | The value is unknown in this version. |
| ## `UNSPECIFIED` | Not specified. |