What is defined as a boundary that prohibits fires or their effects from crossing between friendly forces?

A Restrictive Fire Line is defined as a boundary established to prevent fires or their effects from moving across into areas occupied by friendly forces. This line is crucial for ensuring the safety of friendly units and to mitigate the risk of friendly fire incidents. By implementing a Restrictive Fire Line, military operations can allow artillery or close air support to be used effectively and safely, while maintaining clear spatial awareness regarding where friendly forces are located.

In contrast, a Coordinated Fire Line is meant to facilitate the engagement of targets beyond a specified point without restrictions but does not provide the same level of safety for friendly forces. A Phase Line is primarily used for tracking progress during an operation, and while it may coincide with boundaries, it does not serve the same protective function. Lastly, while a Boundary may delineate different units or sectors, it lacks the specific safety intent of a Restrictive Fire Line regarding the control of artillery or air support fire.