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Why are some of my items for sale removed by eBay when I was allowed to list them through the use of ISBN or UPC values using ExternalProductID?
Items can be listed through the API using ISBN or UPC values for ExternalProductID.
Here a quick example of the ExternalProductID container as used in the Item of an AddItem call.
In a small number of cases these items violate Trust & Safety listing policies.
These items will be removed from eBay even though the catalog system will still continue to have the ISBN numbers.
One example is "Teacher's Edition" textbooks used at the University or High School level.
Listings for these types of textbooks will be pulled down by eBay as per the policy described here:
Teacher’s Edition Textbooks
However, the eBay catalog system will continue to have the ISBN numbers for these books.
The catalog system that eBay uses does not have the ability to remove specific ISBN numbers from the selling flows.
Applications that rely on the eBay response to the AddItem call for determining what ISBN or UPC values are not only supported in the catalog, but that are allowed by eBay, will need to implement some kind of exclusion list.
As ISBN or UPC values become known to violate listing policies, the selling application should add them to the exclusion list so that sellers are not able to list these items.