glibc/ctype/Versions

libc {
  GLIBC_2.0 {
    # global variables
    __ctype_b; __ctype_tolower; __ctype_toupper;

    # i*
    isalnum; isalpha; isascii; isblank; iscntrl; isdigit; isgraph; islower;
    isprint; ispunct; isspace; isupper; isxdigit;

    # t*
    toascii; tolower; toupper;
  }
}