10 U.S.C. § 12241: Warrant officers: grades; appointment, how made; term

(a) The permanent reserve warrant officer grades in each armed force are those prescribed for regular warrant officers by section 571(a) of this title. (b) Appointments in permanent reserve warrant officer grades shall be made in the same manner as is prescribed for regular warrant officer grades by section 571(b) of this title. (c) Appointments as Reserves in permanent warrant officer grades are for an indefinite term and are held during the pleasure of the Secretary concerned.