Product IDs are used to help Walmart's systems identify the item you are selling, determine if the same item is sold elsewhere and establish variant groups across different Sellers.
There are four types of product IDs that Walmart accepts:
Global Trade Item Number
General purpose, used worldwide
Universal Product Code
General purpose, used primarily in United States, Canada, United Kingdom, Australia, New Zealand
International Standard Book Number
Paperback, Hardcover and Electronic Books
10 or 13 digits
International Standard Serial Number
Newspapers, Journals, Magazines and Periodicals
If you have a different type of product ID, you must convert it into one of these four types.
Check with the organization that manages your type of product ID to learn how to convert it into an acceptable type.