Some printers also use a B&W RA-4 paper -- it produces a true, near-neutral image, but exposes and processes in their automated machinery. With their magazine setups for the rolls of paper, it's not even a big deal for them to switch from color to B&W paper, as long as it all works with RA-4.

The bad news is, the RA-4 B&W isn't any more permanent than a common color print, compared to the potential longevity of a properly processed silver gelatin print.