To enable Assistive Technologies to read the elements on your slide in the correct order, you must define the reading order.
PowerPoint does not arrange the elements according to their position on the slide, but according to the order in which the elements were inserted on the slide. Therefore, the reading order is usually not correct and you need to check it after completing your slide.
Checking and Changing the Reading Order
Open the Review tab in the ribbon and click on the Check Accessibility button. In the menu that opens, select the Reading Order Pane option. The Reading Order pane now opens.
You can now adjust the reading order. At the top is the element that is read first. Ideally, this should be the title of your slide. If you click on an entry in the Reading Order pane, the corresponding element will be selected on your slide. You can change the order of the elements in the Reading Order pane using Drag & Drop or alternatively using the two arrow buttons (Move Up and Move Down), which you will find at the top right of the Reading Order pane.
There is a checkbox in front of each entry. If the checkbox is ticked, the element is read. If it is deactivated, the element is marked as decorative and is not read. You can read more about this in the following section.
Marking Elements as Decorative in the Reading Order Pane
Elements that are not relevant in terms of content and should not be taken into account by Assistive Technologies can be marked directly as decorative in the Reading Order pane. To do this, deactivate the checkbox in front of the respective element. The position of decorative elements in the reading order does not matter, as they are skipped and do not appear in the Logical Document Structure of your accessible PDF. If you want the element to be included in the reading order after all, activate the checkbox again. You can find out more in Add Alt Text or Mark Object as Decorative.
Edit Alt Text in the Reading Order Pane
If you have assigned an alt text to graphic elements, this is displayed in the Reading Order pane. If you select the entry for a graphic and click on it a second time, you can add or edit the alt text directly here. You can find out more in Add Alt Text or Mark Object as Decorative.