Law School Discussion

Origin of phrase 1L where did this start and what is the TRUE meaning ?

If anyone has information about this, please post up... I am assuming that the L in 1L (or 2L or 3L for that matter) denotes LAW, however i am interested in confirming this and discovering the origin of this phrase. 


Well, I know med-students refer to themselves as M1, M2, etc.
We can deduce that the m= medicine/med student and thus l = law/ law student

At my UG everyone has this type of designation. 1-4 and then some letters denoting your college. e.g. 3BA=Junior in business admin, 4EG=Senior in engineering