What does BUPERSMAN 3420220 28B mean?

BUPERSMAN 3420220 28B refers to a specific section of the Bureau of Naval Personnel Manual (BUPERSMAN), which outlines policies and procedures related to Navy enlisted personnel. The "3420220" section deals with topics such as enlistment, evaluation, and retention, while "28B" likely specifies a particular subset or instruction within that section. The manual serves as a comprehensive guide for managing personnel administration in the Navy.