What is the defining characteristic of a circular sheaf?

A circular sheaf is defined by its radius, which typically measures the area of effects for a particular fire mission. The characteristic of having a radius greater than 100 meters distinguishes it from other fire patterns that may have smaller radii. This larger radius allows for more extensive coverage of the target area, making it effective for engaging dispersed targets or for operations where more area is needed to ensure the desired impact on the enemy.

In contrast, the other options present characteristics that do not align with the definition of a circular sheaf. For instance, a hexagonal shape is not applicable as it describes a different pattern entirely. The requirement of a warning order pertains more to the command and communication aspects of calling for fire rather than the physical characteristics of the sheaf itself. Lastly, a radius less than 100 meters would classify the sheaf differently, potentially as a smaller or more localized pattern, which is not what characterizes a circular sheaf.