The fixed side on non-British bikes with that style adjustable cup is often a standard cup with two flats that can be removed with the proper tool or the Sheldon Brown tool. The Sheldon Brown tool can work on the British fixed cups with the raised section if the cup isn't too tight, but the raised section means less surface for the Sheldon Brown tool to grasp and sometimes this means you'll need the fixed cup tool from BikeSmithDesign: