why geoIdTo in ShipmentCostEstimate

[Divesh Dutta]

Hello all,
          I am not getting purpose of geoIdFrom and geoIdTo in 
ShipmentCostEstimate entity.What I guess is it simply specifies source and 
destination for shipment.If this is the case then how will we handle the case 
if shipment is in part.I mean if I want to ship data from warehouse to 
customer's home.In this case geoIdFrom=warehouse and  geoIdTo=customer's 
home.But what if there are two or three terminals in between. 
Thanks in advance
Regards
Divesh Dutta