For Utf-8, there are only a small number of characters that are invalid and they could be escaped to non-character code-points or even to a small region of the Private Use Area (for example FFF00-FFFFF). ###>For Utf-8, there are only a small number of characters that are invalid and they could be escaped to non-character code-points or even to a small region of the Private Use Area (for example FFF00-FFFFF).