We recently integrated the service codes 92,93 for UPS SurePost in our project. The API endpoint being used is
https://onlinetools.ups.com/webservices/Ship
However, we don't see the ReferenceNumber on the shipping label that we passed in the UPS API. Digging more into the docs gave this https://www.ups.com/worldshiphelp/WSA/ENU/AppHelp/mergedProjects/CORE/SHIPMENT/Process_a_UPS_SurePost_Shipment.htm
Under point #4 it says that Reference numbers do not print on standard SurePost labels and that a a "Doc label" is required for reference numbers However, I am clueless how to provide this in the API, I searched the docs here https://developer.ups.com/api/reference?loc=en_US#operation/Shipment
But could not find anything for my requirement
Can anyone please help on this? Thanks in advance.