All persons subject to military duty under the constitution of this state and not exempt therefrom by the provisions of this act, and such other persons as shall voluntarily enroll themselves, shall be divided into three (3) classes, to wit: One consisting of the federally recognized national guard, which shall be known as the “Kansas army and air national guard”; one consisting of those able-bodied male citizens prescribed and contemplated in article 8 of the constitution of this state not in the “Kansas army and air national guard” which shall be known as “the militia”; and one to consist of all those subject to military duty, but not included in the “Kansas army and air national guard” or “the militia” to be known as the “Kansas military reserve.”