OCTALDIGIT [0-7]
UCHARLOWERCASE \\u{HEXDIGIT}{4}
UCHARUPPERCASE \\U{HEXDIGIT}{8}
-ID_NONDIGIT {NONDIGIT}|{UCHARLOWERCASE}|{UCHARUPPERCASE}
+ID_EXTRA_CHAR (":"|".")
+ID_NONDIGIT {NONDIGIT}|{UCHARLOWERCASE}|{UCHARUPPERCASE}|{ID_EXTRA_CHAR}
IDENTIFIER {ID_NONDIGIT}({ID_NONDIGIT}|{DIGIT})*
ESCSEQ \\(\'|\"|\?|\\|a|b|f|n|r|t|v|{OCTALDIGIT}{1,3}|u{HEXDIGIT}{4}|U{HEXDIGIT}{8}|x{HEXDIGIT}+)
%%