AI-generated Key Takeaways
- 
          The document describes an enum detailing possible ad serving statuses. 
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          Various statuses exist, including those for no specified value, unknown values, and different optimization strategies like based on CTR, CTR * Conversion, rotating ads, and indefinitely rotating ads. 
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          There is also a status indicating when ad serving optimization status is unavailable. 
Enum describing possible serving statuses.
| Enums | |
|---|---|
| 
 | No value has been specified. | 
| 
 | The received value is not known in this version. This is a response-only value. | 
| 
 | Ad serving is optimized based on CTR for the campaign. | 
| 
 | Ad serving is optimized based on CTR * Conversion for the campaign. If the campaign is not in the conversion optimizer bidding strategy, it will default to OPTIMIZED. | 
| 
 | Ads are rotated evenly for 90 days, then optimized for clicks. | 
| 
 | Show lower performing ads more evenly with higher performing ads, and do not optimize. | 
| 
 | Ad serving optimization status is not available. |