5 Lexical conventions [lex]

An unevaluated-string shall have no encoding-prefix.

Each universal-character-name and each simple-escape-sequence in an unevaluated-string is replaced by the member of the translation character set it denotes.

An unevaluated-string that contains a numeric-escape-sequence or a conditional-escape-sequence is ill-formed.

An unevaluated-string is never evaluated and its interpretation depends on the context in which it appears.