If you want one or more articles to flow horizontally only, select the Horizontal Swipe Only option in the Article Properties dialog box. Users navigate “flattened articles” by swiping left and right rather than up and down.
A. Unflattened article B. Flattened article
Only the first page of a flattened article shows up in the TOC, but all the pages appear in Browse mode. You cannot flatten an article that is set to Smooth Scrolling.