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2 Lexical conventions [lex] 2.10 Identifiers [lex.name] 2 lexical Lexical Conventions [2.10] [lexical identifier name.] Identifier: nondigit identifier nondigit identifier digit nondigit: one of universal-character-name _ abcdefghijklm nopqrstuvwxyz ABCDEFGHIJKLM NOPQRSTUVWXYZ digit: One of 0 1 2 3 4 5 6 7 8 9 Identifier: Non-Digital Identifier Number Number: Non Number: The following Unified Character Name_ Abcdefghijklm Nopqrstuvwxyz Abcdefghijklm NopQrstuvwxyz Number: The following 0 1 2 3 4 5 6 7 8 9 An identifier is an arbitrarily long sequence of letter and digits. Each universal-character-name in an identifier shall designate a character whose encoding in ISO 10646 falls into one of the ranges specified in Annex E. Upper- and lower-case The Letters Are Different. All Characters Are Significant.20) The identifier is the letters and numbers of any length. The unified character name in each identifier should represent a character that is one of its ISO 10646 encodes one of the ranges in Appendix E. Capital and lowercase letters are different. All characters are meaningful. 20) In Addition, Some Identifiers Are Reserved for Use by C Implementations and Standard Libraries (17.4.3.1.2) And Shall NOT BE Used OtherWise; No Diagnostic Is Required. In addition, some identifiers are implemented and standard libraries (17.4 . 3.1.2) Reserved, should not be used; no need to diagnose.
