Regular= Traditional retirement (most people fall into this category, including LEO/FF/ATC leaving federal service prior to their respective mandatory retirement age (57/56), and those FERS retiring under “Minimum Retirement Age (MRA + 10”).
Optional= Offered an “Early out” because of reductions-in-force (RIF), or agency reorganization.
Mandatory= Special Provisions (LEO/FF/ATC) who wish to stay until forced to retire. Law Enforcement Officers & Firefighters must retire by age 57, and Air Traffic Controllers must retire by age 56.