// subset of CP-437, which itself is ASCII-like.
		//
		// Forbid 0x7e and 0x5c since EUC-KR and Shift-JIS replace those
		// characters with localized currency and overline characters.
		if r < 0x20 || r > 0x7d || r == 0x5c {
			if !utf8.ValidRune(r) || (r == utf8.RuneError && size == 1) {
				return false, false
			}
			require = true
		}
	}
	return true, require
}

FE48          ; disallowed_STD3_mapped ; 005D          # 4.0  PRESENTATION FORM FOR VERTICAL RIGHT SQUARE BRACKET
FE49..FE4C    ; disallowed_STD3_mapped ; 0020 0305     # 1.1  DASHED OVERLINE..DOUBLE WAVY OVERLINE
FE4D..FE4F    ; disallowed_STD3_mapped ; 005F          # 1.1  DASHED LOW LINE..WAVY LOW LINE
FE50          ; disallowed_STD3_mapped ; 002C          # 1.1  SMALL COMMA