38 CFR 21.123: On-job course.

(a) Training establishment. This term means any establishment providing apprentice or other training on the job, including those under the supervision of a college or university or any State department of education, or any state apprenticeship agency, or any State board of vocational education, or any joint apprenticeship committee, or the Bureau of Apprenticeship and Training established in accordance with 29 U.S.C. Chapter 4C, or any agency of the Federal government authorized to supervise such training.

(b) On-job course, An on-job course is pursued toward a specified vocational objective, provided by a training establishment. The trainee learns, in the course of work performed under supervision, primarily by receiving formal instruction, observing practical demonstration of work tasks, and assisting in those tasks. Productive work should gradually increase with greater independence from formal instruction as the course progresses.