 The question of which prior rulings can and cannot be disputed has led to efforts to define which rulings are within the Acharonim era with precision.According to many Rabbis the Shulkhan Arukh is from an Acharon.Some hold that Rabbi Yosef Karo's Beit Yosef has the Halakhic status of a work of a Rishon, while his later Shulkhan Arukh has the status of a work of an Acharon.