Hello, I am trying to create  Dropship POs with script using the following code

_var_ dropshipPO = _record_.create({

                    

type: _record_.Type.PURCHASE_ORDER,

                    

isDynamic: false,

                    

defaultValues: {

                        

shipgroup: 1,

                        

soid: _soId_,

                        

dropship: true,

                        

custid: _customerId_,

                        

entity: vendorId,

                        

poentity: vendorId

                    

}

                

});

I have noticed that the parameters like shipgroup and custid are same as the parameters of the url to create dropship pos. Can anyone tell me how these parameters are being picked by the system? Because on some items these parameters are different even though I cannot find anything different in items themselves.