Which of the following measures is both permissive and restrictive in nature concerning operational areas?

The correct answer is the boundary, which is both permissive and restrictive in nature concerning operational areas. In military operations, a boundary delineates the areas of responsibility between units. It is permissive because it allows the units on either side to conduct operations within their designated areas without interference, promoting coordination and effective engagement of the enemy. However, it is also restrictive because it serves to limit the operational freedom of units by clearly defining where their authority and responsibilities begin and end. This dual nature is essential for maintaining command and control during complex operations.

Other terms like the coordinated fire line, phase line, and fire support coordination line have specific functions. The coordinated fire line is primarily a permissive measure that allows certain types of fire support to be conducted in a designated area without prior coordination. The phase line is a control measure that typically marks specific points in time during an operation and primarily aids in maneuvering forces rather than limiting or allowing operations. The fire support coordination line is mainly used to separate airspace for friendly and enemy fire support, emphasizing control over the use of fire rather than delineating responsibility. Thus, while they all play critical roles in military operations, they do not embody the same dual capacity of permissiveness and restrictiveness as the boundary does.