MAX3222 has internal pull-up or pull-down on DINx and RINx?

The datasheet's "Function Tables" show that RINx can be left open, i.e., there is a pull-up (see "RECEIVER SECTION" for the resistance).
Nothing like this is mentioned for the DINx inputs, and their input current is extremely low, so they are plain CMOS inputs and need to be tied to either VCC or GND.

Hi Clemens,

Thank you for your comment. Please let me ask one more question for RINx.

Regarding DINx, I understand that external pull-up or pull-down is needed at unused.
Regarding RINx, I understand that RINx has internal resistance and it can be left open, but how can you judge it's pull-up, not pull-down?

Best Regards,
Sonoki

The receiver function table shows that an open RINx is interpreted as high.

Hi Clemens,

From receiver table, the ROUT is High at RIN = Open, this is the same with RIN = Low. So I think the internal resistance should be pull-down. Is my understanding correct?

Best Regards,

Sonoki