What does "Space Required" refer to in passenger travel?

"Space Required" in the context of passenger travel refers specifically to the need for seats that have been requested by passengers who are traveling on military orders. This term is often used in military and government travel arrangements where service members may need seats on a flight or transport on a space-available basis.

In this scenario, passengers traveling on military orders are essentially prioritized and given a specific requirement for travel, meaning that their requests for travel specify a need for space on a flight. This reflects the structured system in place for accommodating military personnel who have official travel needs.

Other options address different categories of passengers or situations, but they do not embody what "Space Required" specifically means in this context within military travel. For instance, passengers with no specified travel dates are not contingent upon immediate seat availability, and while available seats for previously accommodated passengers pertain to seating logistics, they do not define the unique requirement associated with military orders.