> Chicken, Guile, S7 support #:foo as self-evaluating keywords; Racket,
> Kawa in procedure calls only (unless quoted).

Thanks! Updated at <https://registry.scheme.org/#hash-syntax>:

#:    Keyword object [Chicken, Guile, S7];
       Keyword marker [Kawa, Racket];
       Uninterned symbol [Gauche]