Functional Cell
A functional cell is a staff grouping organized around similar responsibilities so a headquarters can coordinate specialized work [reeves2018].
The concept matters because headquarters need specialization. Fires, intelligence, sustainment, protection, and other functions cannot be managed as one undifferentiated mass of staff effort. A functional cell creates a stable place where related expertise can develop assessments and recommendations.
Sources
References
[reeves2018] Richard Reeves. (2018). Functional and Integrating Cells within Sustainment Brigade Staffs. The United States Army. https://www.army.mil/article/206360/functional_and_integrating_cells_within_sustainment_brigade_staffs