Final answer:
In the context of conducting BDAs on multiple DPIs, the additional line required after the 9-Line is the DPI Sequence Line, which dictates the order of target engagement.
Step-by-step explanation:
If conducting Battle Damage Assessments (BDA) on multiple Desired Points of Impact (DPIs), the additional line that must be given after the 9-Line and prior to Remarks is the DPI Sequence Line. This line provides the order in which multiple targets, or DPIs, should be engaged. The use of the DPI Sequence Line ensures that the aircraft or other assets conducting the strike can effectively engage each target in a sequence that supports the mission objectives.