In a bowl, combine the flour, baking powder, baking soda, and salt; cut in shortening until the mixture resembles coarse crumbs. Stir in buttermilk; knead dough gently. Roll out to 1 cm thickness. Cut with a 2- 1 cm biscuit cutter and place on a lightly greased baking sheet. Bake at 230ºC or 10-15 minutes or until golden brown.