const unicode.ReplacementChar

5 uses

	unicode (current package)
		letter.go#L11: 	ReplacementChar = '\uFFFD'     // Represents invalid code points.
		letter.go#L209: 		return ReplacementChar, false // as reasonable an error as any

	encoding/json
		decode.go#L1269: 					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
		decode.go#L1276: 					rr = unicode.ReplacementChar

	mime
		encodedword.go#L336: 				buf.WriteRune(unicode.ReplacementChar)