List in two categories

Listing an item in two categories is achieved when the listing is created using the AddItem API. To add a second category, set the value of Item.SecondaryCategory.CategoryID to the numeric category ID of the desired second category.

When listing in two categories, you can use Item Specifics provided at least one of the categories supports this feature. That is, as long as either the primary or secondary category has Item Specifics enabled you can list with Item Specifics.

If both categories support Item Specifics, you still only specify one Item.ItemSpecifics node in your listing request. This is because Item Specifics are intended to describe the item itself, regardless of the category. eBay will store the names and values in the order you specify them.