The Internet provides dozens of websites that chart the ASCII and symbol tables ... symbol using the ALT+ character code. If not, see the “ASCII Decimal, ASCII Hex, or Unicodes” section ...

Essentially, the ASCII table can be used as a giant decoder. The important columns for "The Martian" are the ones labelled "Hex" and "Character." When NASA points to a pair of hexadecimal digits ...

The numerical value, or order, of an ASCII character. There are 128 standard ... represented in decimal (see ASCII chart) or in hexadecimal (see hex chart). THIS DEFINITION IS FOR PERSONAL USE ...