At what point is a gun-target line considered hot?

A gun-target line is considered hot when the firing unit is actively firing. This means that there are actual rounds being fired towards the target, indicating that the precautions and control measures for engaging that target are in effect. Once the firing unit begins its operation, it signifies that the GTL is currently in use and that the safety of marshalling friendly forces and preventing fratricide is paramount.

While the other aspects mentioned involve stages in the firing process, they do not represent the immediacy and engagement of the firing component itself. For instance, simply reporting laid does not equate to active firing; it is merely a preparatory step. Similarly, the reception of a call for fire (CFF) is an integral part of the fire mission process but does not imply that munitions are being deployed. Lastly, the mention of passing the gun-target line in the remarks or restrictions is administrative and does not reflect an active engagement in the battle space. Thus, the active firing status reflects an immediate, operational situation where the gun-target line is clearly established as hot.