Developer for System z Enterprise PL/I for z/OS, Version 3.8, Language Reference Manual
Hexadecimal digits
PL/I recognizes the 16 hexadecimal digits,
0 through 9 and A through F. A through F represent the decimal values
10 through 15, respectively. They are also known as hex digits or
just hex and are used to write constants in hexadecimal notation.