enable pins on RS422 drivers IC
From the schematic you posted I would read it as:

If either enable pin is high OR (not enable) pin is low, all of the outputs are enabled.

The enable inputs are just wired in parallel to the output of the OR-gate. If the function you are imagine is implemented, the schematic is very misleading and there must be a clearer description around in the datasheet.



Update:

The datasheet is indeed very limited, but it gives a link to a more detailed description where you will find a truth-table:



So you can see, there is no distinction between the different inputs or outputs made. So it will behave just as I read it from the schematic above and all outputs are enabled or disabled.