Segment Code, as this column comes in Temporary Schema and it's not saved in the database.
Each activity has it's own Segment Code but, all the Segment Codes have same Alias as well as Column Name in the Temp Schema i.e. Segment code (@segmentCode).
So, before the delivery you can have one split activity, in which you can filter out the recipients who have Segment Code as Empty and send the delivery to only those which have Segment Code value populated.
Delivery code and segment code are two different attributes and they are populated in Adobe mart at two different levels. Delivery code is an attribute of Delivery (NMSDelivery) vs. Segment Code is an attribute of the universe targeted in a delivery and the proper location for segment code attribute is BroadLogRcp table.
The segmentation of the campaign universe is not always dependent on # of deliveries. It is possible to have more segments (via split activity node) but a single delivery (behavior analysis).
I recommend to re-evaluate the use of these codes in your system.