NB: All of the tracker issues, posted by 'accessible_for_vip', are based on the theme 'Accessible for VIP' (https://moodle.org/plugins/view.php?plugin=theme_accessible_for_vip) which is developed for people who are blind or have a low vision. All of the (code)solutions are based on the files which belong to this specific theme and are only usable with this theme at this moment (but it is also possible to include the solution in general source code).
When you are in a quiz, the navigation on the left side of the page is not a list of links. So, with a screenreader it is impossible to read the links in a structured way and the numbers for the navigation are not marked as items of a list. When you put the links in a list (<ul><li>...linkitem...</li></ul>, it is possible to find the list of numbers with a screenreader by pressing the quick navigation button for lists.
To improve the accessibility of the numbers for the quiz navigation, we have changed the 'mod/quiz/renderer.php' file, which is shown below (for the theme: theme/accessible_for_ vip/renderers.php):