opinion european central bank juli request commiss european commun articl council regul ec octob articl treati establish european commun draft commiss regul ec minimum standard treatment tariff harmonis index consum price con june european central bank ecb receiv request commiss european commun ecb opinion draft commiss regul ec abovement topic hereinaft refer quot draft regul quot document refer number sg draft regul transmit ecb object draft regul establish minimum standard treatment tariff harmonis index consum price tariff price consider impact develop consum price indic price expenditur weight relev item signific consider scope procedur differ treatment tariff price consum price indic potenti sourc compar ecb support measur propos commiss european commun opinion publish offici journal european commun frankfurt main juli presid ecb willem duisenberg