The AppView widget is available in v3. If you are running v2.3.4 or earlier, it is not included. You can download v3 here: Downloads.
As one of only two widgets that were created specifically for jQuery Mobile (see also ListView), the wijappview widget is a container UI made up of a menu to the left, and a content page to the right. The content page can contain a header in addition to its content. When the user clicks a menu item, AppView uses AJAX to inject the corresponding content into the DOM content page.
The wijappview widget is contained in the jquery.wijmo.wijappview.js file in Wijmo-Complete.
For a listing of all of the options, methods, and events available on this widget, please see the API docs for wijappview.