ONIGENC_IS_CODE_ASCII  246 enc/emacs_mule.c   if (ONIGENC_IS_CODE_ASCII(code)) return 1;
ONIGENC_IS_CODE_ASCII  247 enc/euc_jp.c     if (ONIGENC_IS_CODE_ASCII(code)) return 1;
ONIGENC_IS_CODE_ASCII  223 include/ruby/encoding.h #define rb_enc_isascii(c,enc) ONIGENC_IS_CODE_ASCII(c)
ONIGENC_IS_CODE_ASCII  918 regint.h         (ONIGENC_IS_CODE_ASCII(code) && ONIGENC_IS_CODE_WORD(enc,code))