Fold type
The named way panels fold and nest, such as gatefold, roll fold, or accordion. It decides panel widths, page order, and which side faces out.
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What it is
Fold type names the geometry and sequence of a folded piece. A gatefold brings two outer panels together like doors. A roll fold wraps panels inward one after another, which is the common letter-fold brochure: an A4 sheet rolled into three roughly 99mm panels is the DL leaflet in every hotel rack. An accordion or Z fold alternates direction into a zigzag.
Choose it before laying out panels, not at the end. Accordion panels can usually stay equal, while roll-fold panels that tuck inside need to be slightly narrower. A gatefold needs room where its two leaves meet. Stock thickness, grain, coatings, and finishing tolerances determine the exact allowance.
Gotcha: 'tri-fold' only says there are three panels. It does not tell the printer whether you mean a roll fold or a Z fold, and those put the back panel and panel widths in different places. Name the fold, number the panels, show inside and outside, and add arrows for the sequence.
Ask AI for it
Create an Adobe InDesign folding diagram for a [gatefold / roll fold / accordion fold]. Show trimmed flat size, finished size, exact panel widths, inside and outside views, numbered panels, and arrows for each fold in sequence. Put fold and score lines on a nonprinting technical layer, keep text 5mm clear of them, account for narrower nesting panels on a roll fold, and export the proof as PDF/X-4 with a small folded thumbnail beside the flat artwork.