c - Width prefixes to string constants -

the latest version of c standard provides width prefixes string constants e.g. u8"a" single preprocessing token.

does whether 1 or 2 preprocessing tokens depend on exact letters in prefix? e.g. case u9"a" still 2 preprocessing tokens?

c11 specifies in 6.4 string literal 1 of pre-processing tokens:

preprocessing-token:     header-name     identifier     pp-number     character-constant     string-literal     punctuator     each non-white-space character cannot 1 of above 

hence u8"a" single token because string literal section 6.4.5 lists valid option:

string-literal:     encoding-prefix(opt) " s-char-sequence(opt) " encoding-prefix:     u8     u     u     l 

the sequence u9"a" not string literal because u9 not 1 of valid prefixes.

the u9 (from reading) treated identifier while "a" string literal, 2 separate pre-processing tokens.