Export Reference Number
From UG
An export reference number is a unique, consecutive number assigned by an export operator at the time they create a CT record and will always include a 2 letter code to define the MOT.
There are 3 types of MOT's that can be applied for export shipments, Air Ocean & Trucking and each have a unique two letter code to identify them:
AE = air exports SE = for sea (aka ocean) exports TR = for any type of trucking exports