Possible customer acquisition goal optimization modes.

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

| Enums ||
|---|---|
| ## `TARGET_ALL` | The mode is used when the campaign optimizes for all customers, which is the default value. |
| ## `TARGET_SPECIFIC` | This mode configures the campaign to target only customers who have previously interacted but are now lapsed or disengaged. |
| ## `UNKNOWN` | Used for return value only. Represents value unknown in this version. |
| ## `UNSPECIFIED` | Not specified. |