is_alnum         2229 nkf.c          		} else if (!is_alnum(prev0)) {
is_alnum         2601 nkf.c                          c1=='-'||c1=='_'||is_alnum(c1) ) continue;
is_alnum         2895 nkf.c                  if (!( (c=='+'||c=='/'|| c=='=' || c=='?' || is_alnum(c))))