NCO

In Starfleet, an NCO (Non-Commissioned Officer) was a crewperson who had not completed the four-year Starfleet Academy course. Enlisted crewmen receive basic training, along with any specific courses required for their position before their posting. As with commissioned officers, there was a rank structure among enlisted crew. The term "non-commissioned officer" refers specifically to any enlisted personnel given authority over other personnel.

NCO Recruits

These are the characters that underwent NCO training, and might know each other from their time in Starfleet Bootcamp.

NCO

From Star Trek: Theurgy Wiki

NCO Recruits