Which chapter of the NISPOM may not apply to all facilities?

Chapter 4 of the National Industrial Security Program Operating Manual (NISPOM), which deals with classification and marking, may not apply to all facilities because not every facility handles classified information. The implementation and adherence to classification and marking protocols depend on a facility's specific role and scope of work involving classified materials. Facilities that do not deal with classified information are not required to follow the guidelines set forth in this chapter, making it distinct from the other chapters that pertain more broadly to security policies, physical security measures, and personnel security requirements that are generally applicable across various facilities regardless of their classification activities.

In contrast, the other chapters—covering security policies, physical security, and personnel security—set foundational requirements that typically apply to all facilities participating in the NISP regardless of their classification status.