What method of control tells the FDC the total time to engage a target?

The method of control that communicates to the Fire Direction Center (FDC) the total time to engage a target is best described by the term "Duration." Duration specifies how long the artillery will engage the target, allowing the FDC to calculate the necessary adjustments and timing for fire support. Understanding this concept is crucial for coordinating effective artillery fire, as it ensures that rounds will land correctly within the intended timeframe for maximum impact.

In artillery operations, "Time on target" refers to the specific moment at which the rounds should impact the target, which is a related but distinct concept. While "Time" could refer to various chronological aspects of the mission, it does not specifically convey the total firing period. "Interval," meanwhile, is concerned with the spacing between rounds or actions rather than the overall engagement duration. Thus, "Duration" is the most accurate term for indicating the total time dedicated to engaging a target.