Surfaces available to target in reach forecasts.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v23/enums/reach_plan_surface.proto)

| Enums ||
|---|---|
| ## `DISCOVER_FEED` | Discover feed ad surface. |
| ## `GMAIL` | Gmail ad surface. |
| ## `GOOGLE_DISPLAY_NETWORK` | Google Display Network ad surface. |
| ## `IN_FEED` | In-Feed ad surface. |
| ## `IN_STREAM_BUMPER` | In-Stream bumper ad surface. |
| ## `IN_STREAM_NON_SKIPPABLE` | In-Stream non-skippable ad surface. |
| ## `IN_STREAM_NON_SKIPPABLE_THIRTY_SECONDS` | In-Stream non-skippable (30 seconds) ad surface. |
| ## `IN_STREAM_SKIPPABLE` | In-Stream skippable ad surface. |
| ## `SHORTS` | Shorts ad surface. |
| ## `UNKNOWN` | The value is unknown in this version. |
| ## `UNSPECIFIED` | Not specified. |