Final answer:
The Blue Book identifies an NCO as a technical expert, instructor, and mentor, highlighting the multi-dimensional role NCOs play within the military in guiding junior service members.
Step-by-step explanation:
The Blue Book identifies the Noncommissioned Officer (NCO) as a technical expert, instructor, and mentor. The role of an NCO is multifaceted, involving not just technical skills but also responsibilities towards personnel development. As a mentor, an NCO guides and supports junior service members, imparting experience and knowledge to foster their professional and personal growth within the military organization.