WordPress provides a widget which aggregates all pages into an A to Z listing. The widget includes just
the letters as links to the A-Z Index page. Also provided is an implementation for the A-Z Index page.
If a letter doesn’t have any pages then the widget will display the letter unlinked; likewise the index page
will omit the display for that letter entirely.
Both the Widget and Index page can be section-targeted or global-targeted. i.e. they can limit their output
to displaying only the pages below a single top-level parent page or they can display the entirety of the