https://www.ou.org/holidays/the_thirty_nine_categories_of_sabbath_work_prohibited_by_law/ https://www.ou.org/holidays/the_thirty_nine_categories_of_sa... outlin

https://www.ou.org/holidays/the_thirty_nine_categories_of_sabbath_work_prohibited_by_law/ https://www.ou.org/holidays/the_thirty_nine_categories_of_sa... outlines those "clear boundaries" in detail from a pre-medieval or early medieval perspective.