The VOIDRUNNER'S CODEX is coming! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
untested, but 8x10 would be a 8x10 picture frame for artwork/maps and while also providing enough extra border for ring-punch binders without affecting the text??
AFAIK, the only thing 8x10 is standard for is photographic prints. Maybe it has something to do with a machine they use for preparing page images for print?