The Google product taxonomy
The Google product taxonomy lists all possible values for the 'google product category' attribute. The taxonomy is a tree of categories that describe product families. At the highest level, it is arranged into verticals, which refer to broad categories of products. For example, Electronics is a vertical. The subcategories of these verticals are more specific. Each layer breaks the vertical into a smaller product family. So the string for a category like MP3 Players would look like this: Electronics > Audio > Audio Players & Recorders > MP3 Players.
When the 'google product category' attribute is required, you'll use a value from the taxonomy, either an ID number or the full path of the product category. For more information on this attribute and how to format the attribute values, learn more about categorizing your products.