No-Lone Zone definition in Computer Security terms:
Definition(s): An area, room, or space that, when staffed, must be occupied by two or more appropriately cleared individuals who remain within sight of each other. See two-person integrity (TPI).
Source(s): CNSSI 4009-2015 (CNSSI 4005, NSA/CSS Manual Number 3-16 (COMSEC))
reference: CSRC Glossary