Simplex / duplex printing
Simplex prints one face of a sheet; duplex prints front and back. Duplex also needs the right long-edge or short-edge flip direction.
See it
What it is
Simplex prints on one side of each sheet. Duplex prints on both. A duplex job also needs a binding edge: long-edge flip turns like a book, while short-edge flip turns like a calendar. For landscape pages, the choice that feels natural can reverse, so judge it from the actual page orientation.
Use simplex for one-face signs, forms that must stay blank on the back, or output that will be mounted. Use duplex for books, reports, cards, and anything where saving sheets or pairing front and back matters. Commercial presses may call printing both sides in one pass perfecting.
Gotcha: selecting duplex does not guarantee that fronts and backs align perfectly. Paper can move, and thin stock can show dark artwork through from the reverse. Build safe tolerances for backup registration, check opacity, and run a physical proof with page numbers before committing the full job.
Ask AI for it
Configure this CUPS print job for duplex output using `sides=two-sided-long-edge`; change it to `sides=two-sided-short-edge` only when the supplied page orientation needs calendar-style flipping. Preserve intentional blank pages, add visible page numbers to one proof set, and return a front-to-back sheet map that flags upside-down backs, show-through risks, and any artwork that depends on tight backup registration.