Rabbit 4000 cbm instruction - (de) operand without ioi or ioe?

The description of the Rabbit 4000 cbm instruction states calls (de) “address of I/O register” and states “only (de) is affected by ioi or ioe”.

What happens if neither ioi or ioe is used? What will (de) refer to? Internal I/O? External I/O? Memory?

If the latter, will the instruction work normally for (de) == (hl)?

If yes, it could be very useful for setting or resetting bits in memory, in particular for implementing bitfields.


Experimentally, using an RCM 4110, despite all the wording about “I/O register” in the documentation, the instruction actually just works normally with memory operands like any other instruction.