The reading order can quickly be checked by using the Touch Up Reading Order tool. It is possible to use this tool to add alternate text to images and correct many types of tagging problems that are outlined in the report that Acrobat generates when adding tags to a PDF.
Reading order issues are readily apparent when using the Touch Up Reading Order tool. Each section of contiguous page content appears as a separate highlighted region and is numbered according to its placement in the reading order. It may be helpful to turn off the option “Display Like Elements in a Single Box” to change the order of similar elements that appear to be grouped with one number in the Order.
Within each region, text is ordered left to right and top to bottom. (This order can be changed in the Touch Up preferences.) If a single highlighted region contains two columns of text or text that will not flow normally, divide the region into parts that can be reordered. Because highlighted regions are rectangular, they may overlap somewhat, especially if their page content is irregularly shaped. Unless page content overlaps or is contained within two highlighted regions, no reading order problem is indicated. Page content should belong to no more than one highlighted region.
The reading order of the highlighted regions can be changed by moving an item in the Order panel or by dragging the numbers on the page in the document pane. By reordering highlighted regions on the page, it is possible to make a figure and caption appear in the reading order at the specific point that they are referenced in the text. By changing the order of a highlighted region, the reading order can effectively be changed for an item without changing the actual appearance of the PDF.
To check the reading order with the Touch Up Reading Order tool: