Shower valve installation question

In the process of installing a Delta single handle valve for my shower. The instructions say that cold goes on the right, and hot on the left. Directly below this is the following:

If you are making a back to back or reverse installation (hot on right and cold on left) install the valve body as above, but the water supply lines will be reversed.

Could someone please explain what they mean by a back to back or reverse installation? I don't think it applies, but I have no idea what they're talking about.

Thanks!

Are you installing two faucets?Back to back is installing two faucets
in the wall but two rooms back to back.If you are installing one faucet,
cold right,hot left.

Nope, just one. I think I understand now. Tried to delete the message before anyone read it, but could not. Thanks for the reply!

B2b

Just to give a bit more information and clarify it. When the two valves are back to back, the cold of one is on the same side as the hot of the other, and vice versa, therefore, rather than do a complicated piping job to get the waters on the right sides, the two can be connected directly together, and then one of them has the cartridge reversed to correct the water orientation. It is the same thing as inverting the valve for a shower only installation to increase the flow to the shower head. In this case, you are reversing the ports on a single valve since the hot is now on the right side.

Makes perfect sense now. Thanks HJ!