This article describes the concept of External method ID in Ingrid, its logic and the usage.
What is an External method ID?
External method ID is a unique carrier product identifier stored in a Merchant's WMS or TA system. 
Image 1 - Example of an external method ID PAR
Setup Guidance
Background
In your 3PL, WMS (Warehouse Management System) or TA (Transport Administration) systems, a carrier service is defined with a special code/ID. Just like in Ingrid - every carrier product is defined with a product code seen below a product name. For example, UPS Standard internal Ingrid code is ups-std:
In order to link a chosen shipping option in Ingrid with the shipping method in your WMS, the external method ID is used.
There you have to define a unique identifier of a particular carrier service from your WMS/TA (depending on the booking flow).
Eventually external method ID will land in the delivery information of the order.
Image 2 - External method id in the Delivery information of Ingrid Transport Order
External method id is a mandatory setting to define, otherwise the booking information flow could be unpredictable.
Setting External method id in Ingrid Platform
Steps:
1. Go to Delivery Checkout > Regions > Specific region > Specific carrier product
2. Define an External method id
