Astring.CharCharacters (bytes in fact).
of_int b is a byte from b. None is returned if b is not in the range [0x00;0xFF].
compare b b' is Stdlib.compare b b'.
module Ascii : sig ... endUS-ASCII character support
val pp : Format.formatter -> char -> unitpp ppf c prints c on ppf.
val dump : Format.formatter -> char -> unitdump ppf c prints c as a syntactically valid OCaml char on ppf using Ascii.escape_char