现代编码模型现代编码模型自底向上分为五个层次:抽象字符表ACR(AbstractCharacterRepertoire)编码字符集CCS(CodedCharacterSet)字符编码表CEF(CharacterEncodingForm)字符编码方案CES(CharacterEncodingSchema)传输编码语法TES(TransferEncodingSyntax)