Final answer:
A reporting senior in the United States Navy is required to retain fitreps on officers and chiefevals on CPOs for two years or until detached for over a year, whichever is longer, as per Bureau of Naval Personnel instructions.
Step-by-step explanation:
The question pertains to the duration for which a reporting senior is required to retain copies of fitreps (fitness reports) on all officers and chiefevals (chief evaluations) on all chief petty officers (CPOs) within the United States Navy. According to the Bureau of Naval Personnel (BUPERS) instructions, a reporting senior should retain these reports for a period of two years after the report's ending date or until they have been detached from the reporting senior's duty station for a period longer than one year, whichever is longer. It is crucial for command continuity, performance documentation, and record-keeping integrity that these documents are kept for the specified time frame.