It was both proscriptive and prescriptive.

It prescribed the performance of work from one's own tradition;

and proscribed that from those of others.

(Up to a point: I don't think that either the pro- or the pre-scription was rigorously or unreasonably enforced. Tho, as I have related before, I recall Ewan threatening Isla Cameron with 50 lashes next time she sang an American song.)

≈M≈