Recently Amazon has added the option of using Fedex as a partnered shipper for FBA shipments within SellerCentral. However the documentation has not been updated on how to send the carrier information within the PutTransportContent API.
The UPS carrier name is listed as UNITED_PARCEL_SERVICE_INC.
What is this for Fedex Ground? Can you use Fedex Ground as a partnered shipper within the API, or is this strictly for SellerCentral?