Just because we grew up "knowing" that the opcode is bytes 0-1 of an instruction, does not mean that that "knowledge" is correct. It's what we think we know but that isn't true that is most dangerous.
It is not valid to assert that something is broken when the "breakage" is because something does not meet pre-conceived, but incorrect (or at least incomplete), notions. The opcode is E317. But opcodes are not always in bytes 0-1 of the instruction. Peter Relson z/OS Core Technology Design
