32 CFR 64.3 - Definitions.
(a) Key employee. Any Reservist or any military retiree (Regular or Reserve) identified by his or her employer, private or public, as filling a key position.
(b) Key position. A civilian position, public or private (designated by an employer and approved by the Secretary concerned), that cannot be vacated during war, a national emergency, or mobilization without seriously impairing the capability of the parent agency or office to function effectively, while meeting the criteria for designating key positions as outlined in Department of Defense Directive 1200.7. 1
1 Copies may be obtained from http://www.dtic.mil/whs/directives.
(c) Military retiree categories - (1) Category I. Non-disability military retirees under age 60 who have been retired fewer than 5 years.
(2) Category II. Non-disability military retirees under age 60 who have been retired 5 years or more.
(3) Category III. Military retirees, including those retired for disability, other than categories I or II retirees (includes warrant officers and healthcare professionals who retire from active duty after age 60).
(d) Military retirees or retired military members. (1) Regular and Reserve officers and enlisted members who retire from the Military Services under 10 U.S.C. Chapters 61, 63, 65, 1223, 367, 571, or 573, and 14 U.S.C. Chapters 11 and 21.
(2) Reserve officers and enlisted members eligible for retirement under one of the provisions of law in § 64.3(d) who have not reached age 60 and who have not elected discharge or are not members of the Ready Reserve or Standby Reserve (including members of the Inactive Standby Reserve).
(3) Members of the Fleet Reserve and Fleet Marine Corps Reserve under 10 U.S.C. 6330.