Trimming

Trimming is the area beyond the trimmed page dimensions. Pictures and objects that you want to print to the edge must have trimming.
The trimming is usually 3 mm on each side of a document. This is to avoid white "flashes" caused by page elements on the edge of the paper.
Text and important information, pictures or design elements that are not to be cropped must be placed at least 3 mm from the edge of the end format.

The PDF file for a K-BOOK must be centred and have trimming, including trim marks.