AR 135-210 governs ordering Army National Guard and Army Reserve Soldiers to active duty for specified peacetime purposes.
View AR 135-210 on armypubs.army.mil
AR 135-210 covers active duty to fill Regular Army vacancies and active duty when in a captive status. It sets eligibility, qualification, medical examination, application, approval, and order requirements.
Applications received after requirements have been filled will be returned without further processing. (paragraph 2-1)
Persons in the categories listed below may apply for AD if they meet the qualification requirements in paragraph 23 and the medical examination requirements in paragraph 24. (paragraph 2-2)
Applicants who are ARNGUS Soldiers must have the approval of their State Adjutant General. (paragraph 2-3)
Applicants who are USAR Soldiers must have approval of their major subordinate command CG. (paragraph 2-3)
The AD commitment is for an indefinite period. (paragraph 3-6)