6. To the extent necessary and legally possible, the negotiations may also seek to determine transitional arrangements which are in the interest of the Union and, as appropriate, to provide for bridges towards the foreseeable framework for the future relationship in the light of the progress made. Any such transitional arrangements must be clearly defined, limited in time, and subject to effective enforcement mechanisms. Should a time-limited prolongation of Union acquis be considered, this would require existing Union regulatory, budgetary, supervisory, judiciary and enforcement instruments and structures to apply.