SN74VMEH22501A: Terminal processing

What is the value of DIR? Do yxou ever need to change it?

I need to change it.

Since it is used on a board that can be both  master and  slave, it is used in both directions

I use 3A and 3B connected to GND.

In conclusion, what should I do with 3A and 3B?　3B can also be used as input, so it is recognized that it should not be opened.

Therefore, I thought that 3A and 3B should be connected to GND.  That's fine, right?

Additional confirmation.
When the power is turned on, does the output rise to about 0.6V, when the internal control of the IC begins to be applied?
If so, is there a risk of a short circuit in the direct GND connection?

Yes, if they're both connected to ground it should be ok. Sorry, when I was typing I forgot the device was a transceiver. 

If I'm understanding this question correctly, it partly depends on how long it takes for the device to turn on. If the ramp is long there could be issues but otherwise there's likely no problem with this.

I'm sorry, I'll rephrase. Is there a risk of a short circuit being output before the internal control of the IC is applied?

What do you mean by "internal control of the IC"?

I am afraid that the output will come out while the IC is stable.
If there is such a possibility, I think it should be a pull-down instead of a direct connection to GND.

It would be helpful if you could say that there is no problem with the GND connection (3A and 3B) without such a worry.