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DE??? ?????
?? 4??? ??? ?????? ??? ??? ??.
?? ???? ??? ?????? ??? ??? ??? ????: ?? ??(IT) ??.
International Electrotechnical Commission (IEC), ??? ?????
British Standards Institution (BSI), ??? ?????
SCC, ??? ?????
Guizhou Provincial Standard of the People's Republic of China, ??? ?????