( Relative jumps are a bit special. They're supposed to take
  an argument, but they don't take it so they can work with
  the label system. Therefore, relative jumps are an OP1 but
  when you use them, you're expected to write the offset
  afterwards yourself. )

0x18 OP1 JR,                   0x10 OP1 DJNZ,
0x38 OP1 JRC,                  0x30 OP1 JRNC,
0x28 OP1 JRZ,                  0x20 OP1 JRNZ,


