All apprenticeship programs, including those apprenticeship programs created or maintained by joint labor-management organizations, are subject to the prohibitions of sec. 4 of the Age Discrimination in Employment Act of 1967, as amended, 29 U.S.C. 623. Age limitations in apprenticeship programs are valid only if excepted under sec. 4(f)(1) of the Act, 29 U.S.C. 623(f)(1), or exempted by the Commission under sec. 9 of the Act, 29 U.S.C. 628,in.30.