This position is designated as an "emergency essential" position and the selected candidate will be considered an "emergency essential" employee and will be required to be available, ready, willing, and able to report for duty under all circumstances (e.g., inclement weather, government closings and holidays, lapses in appropriations, non-emergency and emergency situations) for operation 24 hours a day and 365 days per year coverage. Schedule A (Disability Appointment): Documentation of eligibility for employment under Schedule A can be obtained from a licensed medical professional (e.g., a physician or other medical professional certified by a state, the District of Columbia, or a U.S. territory to practice medicine); a licensed vocational rehabilitation specialist (i.e., state or private); or any Federal agency, state agency, or agency of the District of Columbia or a U.S. territory that issues or provides disability benefits.