A hexadecimal self-defining term consists of hexadecimal digits enclosed in apostrophes and preceded by the letter X; for example, X'C49' and X'00FF00FF00'.

Each hexadecimal digit is assembled as its 4 bit binary equivalent. Thus, a hexadecimal term used to represent an 8 bit mask consists of two hexadecimal digits. The maximum value of a hexadecimal term is X'FFFFFFFF'; this allows a range of values -2,147,483,648 - 2,147,483,647.

0 - 0000   4 - 0100   8 - 1000   C - 1100
1 - 0001   5 - 0101   9 - 1001   D - 1101
2 - 0010   6 - 0110   A - 1010   E - 1110
3 - 0011   7 - 0111   B - 1011   F - 1111

When used as an absolute term in an expression, a hexadecimal self-defining term has a negative value if the high-order bit is 1.