Canada
Files should be supplied as a single PDF that contains all of the pages for the book. This file should be exported directly from the design software as "Single Pages" instead of multi-page spreads (for example, an 8.5x11 book should be exported as 8.5x11 pages and not as 17x11 spreads that each have 2 pages)
A minimum of .25" or 1/4" of safe margin is required for all booklets. This means that page numbers, images, text, and any important elements that are not intended to go right to the edge should be at least .25" away from the edges.
This is for two reasons. Firstly, there is some natural variation in the cutting process, and there is no way to guarantee that every booklet will be cut in exactly the same place. Secondly, when sheets are gathered, folded, and inserted into each other, a phenomenon known as "Creep" can occur, especially with thicker paper stocks. Creep is where the bulk of the paper causes the inner pages to extend or "creep" further out than the outermost pages when folded. Below is an exaggerated view of how the inner pages extend beyond the edge of the outer pages when folded (this is for illustrative purposes only, the actual amount of creep is usually between 0"-.125", depending on paper weight and page count).
United States