0xFF is a constant, simply the number 255, written in hexadecimal. It can be used absolutely anywhere, and your clue leads to some forum where someone posts their programs and asks for help with them. There's not even a hint that "this is how the genotype is determined"; it's just nonsense.
The second one is even better. Look, you're now also a fan: VesperLindt - Bond - Bond uses computers - computers need an operating system - Unix
Good, right?