Type defining the ISBNEnabled field that is returned under the FeatureDefinitions container of the GetCategoryFeatures response (as long as 'ISBNEnabled' is included as a FeatureID value in the call request or no FeatureID values are passed into the call request). This field is returned as an empty element (a boolean value is not returned) if one or more eBay API-enabled sites support the ISBN product identifying feature.

To verify if a specific eBay site supports the ISBN product identifying feature (for most categories), look for a 'true' value in the SiteDefaults.ISBNEnabled field.

To verify if a specific category on a specific eBay site supports the ISBN product identifying feature, pass in a CategoryID value in the request, and then look for a true value in the ISBNEnabled field of the corresponding Category node (match up the CategoryID values if more than one Category IDs were passed in the request).