| HTML Entity (dec) | ? |
| HTML Entity (hex) | ? |
| UTF-8 (hex) | 0x3f |
| UTF-8 (dec) | 63 |
| UTF-16-BE (hex) | 0x3f |
| UTF-16-BE (dec) | 0, 63 (2 bytes) |
| UTF-32-BE (hex) | 0x3f |
| UTF-32-BE (dec) | 0, 0, 0, 63 (4 bytes) |
| C/C++/Java source code | "\u003f" |
| Python source code | "\u003f" |