Hi rossc47800017,
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.
For more details click here Targeting data
Regards,
Venu