OS缩写的意思

PEL ETC LJ OSUCFM DIL PS AT DOW EGR API APN APC DC AHGOLEOD IAQ THC SE AR SR P.E.O. ESS MPN ARIS EOC PEFC ES WWTS AFOC ED FRS ASBL NFAP UKWAS AS OHS C&T CFC SBR EI CASS AC TSP LOI RU EM WBGT SM TS ACODS PER IPCC FFES RORSAT NFPARR APFTPOS APL FFCS TPES FCLPRC MP