本文件规定了一组基本的XML编码规则（basic-XER），可用于为记录ITU-T X.680 | ISO/IEC 8824-1和记录ITU-T X.681 | ISO/IEC 8824-2中定义的类型的值推导传输语法。本文档还指定了一组规范的XML编码规则（CXER），这些规则为基本的XML编码规则提供约束，并为任何给定的ASN生成唯一的编码。1个值本文档进一步指定了一组扩展的XML编码规则（extended-XER），它添加了更多的编码器选项，还允许ASN。1个说明符，用于改变BASIC-XER生成的编码这些编码规则的规范中隐含着它们也用于解码。 本文档中指定的编码规则: -在交流时使用； –？用于显示值和/或使用常用XML工具（如浏览器）处理值是选择编码规则的主要考虑因素的情况； –允许通过为建议ITU-T X.680 | ISO/IEC？8824？1中描述的所有形式的可扩展性添加额外值来扩展抽象语法。 本文档还规定了XER编码指令的语法和语义，以及它们的赋值和组合规则。XER编码指令可用于控制特定ASN的扩展XER编码。1.类型。

This document specifies a set of basic XML Encoding Rules (BASIC-XER) that may be used to derive a transfer syntax for values of types defined in Rec. ITU-T X.680 | ISO/IEC 8824-1 and Rec. ITU-T X.681 | ISO/IEC 8824-2. This document also specifies a set of Canonical XML Encoding Rules (CXER) which provide constraints on the basic XML Encoding Rules and produce a unique encoding for any given ASN.1 value.？This document further specifies a set of extended XML Encoding Rules (EXTENDED-XER) which adds further encoders options, and also allows the ASN.1 specifier to vary the encoding that would be produced by BASIC-XER.？It is implicit in the specification of these encoding rules that they are also used for decoding. The encoding rules specified in this document : –？are used at the time of communication; –？are intended for use in circumstances where displaying of values and/or processing them using commonly available XML tools (such as browsers) is the major concern in the choice of encoding rules; –？allow the extension of an abstract syntax by addition of extra values for all forms of extensibility described in Rec. ITU-T X.680 | ISO/IEC？8824？1. This document also specifies the syntax and semantics of XER encoding instructions, and the rules for their assignment and combination. XER encoding instructions can be used to control the EXTENDED-XER encoding for specific ASN.1 types.