The shipping cost model offered by the seller.
Flat shipping model: the seller establishes the cost of shipping and cost of shipping insurance, regardless of what any buyer-selected shipping service might charge the seller.
Calculated shipping model: the cost of shipping is determined in large part by the seller-offered and buyer-selected shipping service. The seller might assess an additional fee via PackagingHandlingCosts.
Freight shipping model: the cost of shipping is determined by a third party, FreightQuote.com, based on the item location (zip code). Currently, Freight can only be specified on input via eBay Web site, not API.
Free shipping. Returned only by GetSearchResults and GetProducts. This field is output-only so if you want to use AddItem to specify a free Shipping Cost, specify 0 in Item.ShippingDetails.ShippingServiceOptions.ShippingServiceCost.
The seller did not specify the shipping type.
The seller specified one or more flat domestic shipping services and one or more calculated international shipping services.
The seller specified one or more calculated domestic shipping services and one or more flat international shipping services.
Freight shipping model: freight shipping may be used when flat or calculated shipping cannot be used due to the greater weight of the item. See "Specifying Freight Shipping" in the Shipping chapter for details on freight shipping.
Reserved for future use.