ECSC - PRODUCTION - SYSTEM OF PRODUCTION QUOTAS FOR STEEL - SYSTEMS ESTABLISHED SUCCESSIVELY SINCE 1980 - CARRYNG FORWARD OF QUOTAS NOT USED UP IN THE PRECEDING QUARTER - FACILITY ACCORDED BY THE VARIOUS SYSTEMS - DUTY OF THE COMMISSION TO ENSURE ITS CONTINUED AVAILABLITY ( COMMISSION DECISIONS NOS 2794/80/ECSC AND 1831/81/ECSC )