What kind of outline do direction signs provide?

Direction signs serve the purpose of providing important information to pilots and ground personnel by designating taxiway intersections. These signs guide aircraft on the ground, helping them navigate safely from one area to another, particularly at busy airports where multiple taxiways intersect. By identifying intersections, direction signs facilitate efficient movement, ensuring that pilots are aware of their surroundings and the available routes. This minimizes confusion and enhances overall airport safety and operational efficiency.

The other options relate to different aspects of airport operations. For example, runway boundaries are indicated by other types of signs, ILS critical areas are marked to protect the integrity of instrument approaches, and special operation locations pertain to designated areas for particular airport activities, none of which specifically describe the navigational function of direction signs.