Issur VeHeter HaArokh is a 15th-century composition on dietary laws (referred to as “issur v’heter,” which translates as “forbidden and permitted”). The author was an Ashkenazi legal authority and a contemporary of the Trumat HaDeshen, but his exact identity is a matter of debate. Issur VeHeter HaArokh was a central source upon which Rav Moshe Isserles (the Rema) relied in his legal rulings.