The CUSTOMER_ID is how we identify a unique Trip Group in our system. If you are sending us your trips from a GDS, it will often be the same as the DK number. However, the GDS UDID number can also be used as the CUSTOMER_ID to associate those trips under a single Trip Group.
There can be many trips to a single CUSTOMER_ID and there can be many CUSTOMER_IDs associated with the same Trip Group Name. The CUSTOMER_ID allows our system differentiate those Trip Groups from each other.
Because the GDS is used as a reservation platform for corporate bookings, the PNR often includes various fields used for corporate reporting. User Definable Interface Data (UDID) are pieces of information attached to a booking for reporting purposes.