On September 3rd, 2014, we introduced
callouts extensions: additional text you can include with your Google search ads that provide detailed information about your business, and products and services you offer. Starting today, all AdWords API versions can now manage callouts using the existing Feed API,
similar to other feeds.
Feeds for callouts are mapped to feed placeholder type 17, with only one string field. See the
feed placeholder documentation for more information.
- Ray Tsang, AdWords API Team