Extreme community hardship. A situation that, because of a Reserve member's mobilization, may have a substantially adverse effect on the health, safety, or welfare of the community. Any request for a determination of such hardship will be made by the Reserve member and must be supported by documentation, as required by the Secretary of the Military Department concerned.

Inactive National Guard (ING). Members of the National Guard in an inactive status in the Ready Reserve and attached to a specific National Guard unit. These members do not participate in training activities but mobilize with their unit of assignment or with other units within their State on partial or full mobilization. They are not subject to a call-up pursuant to 10 U.S.C. 12304.

Individual Ready Reserve (IRR). A manpower pool within the Ready Reserve of each of the RCs consisting of individuals who have had some training or who have served previously in the AC or in the Selected Reserve, and may have some period of their MSO remaining pursuant to 10 U.S.C. 651. The IRR consists of members of the Ready Reserve who are not in the Selected Reserve or the ING. Additionally, the IRR also includes some personnel who are participating in officer training programs or in the Armed Forces Health Professions Scholarship and Financial Assistance Programs.

Key employee. Any non-federal employee occupying a key position within an agency, company, local government, or organization.

Key position. A public or private civilian position, not a job series, designated by the employer and approved by the Secretary of the Military Department concerned) that cannot be vacated during war or national emergency.

Mobilization. The process by which the Armed Forces of the United States, or part of them, are brought to a state of readiness for war or other national emergency.

Ready Reserve. The Selected Reserve and Individual Ready Reserve liable for active duty as prescribed by law.

Selected Reserve. Those units and individuals within the Ready Reserve designated by their respective Military Service and approved by the Joint Chiefs of Staff as so essential to initial wartime missions that they have priority over all other reserves.