If an ASCII character is encountered outside of the valid fundamental I.F. components (token, remark, preprocessor directive, or whitespace), the character is illegal and causes an error in compilation.

UnrecognizedCharacters ::= [#0-#255]* – (Token | OneLineRemark | MultilineRemark | Preprocessor | S)

  See also:  [Punctuators] [Operators] [Keywords]
[Identifiers] [Numbers] [String literals] [Remarks]
[Preprocessor directives] [Whitespace] [Unrecognized characters]