AI-generated Key Takeaways
- 
          BaseCustomFieldValue represents the value of a CustomField for a specific entity. 
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          It is used by several services including CreativeService, ForecastService, LineItemService, OrderService, ProposalLineItemService, and ProposalService. 
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          BaseCustomFieldValue has a dependency on the Proposal object. 
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          It is the base class for CustomFieldValue and DropDownCustomFieldValue. 
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          The required attribute for BaseCustomFieldValue is customFieldId, which is a long representing the ID of the CustomField it belongs to.
The value of a CustomField for a particular entity.
- Namespace
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               https://www.google.com/apis/ads/publisher/v202505
| Field | |
|---|---|
| 
                            | 
                            Id of the  |