Jari Laine in both cases the items will be written to "APEX Session memory" in the database. Here are the reasons: 1: When you have a application computation, the processing is done in the database and therefore is saved in your APEX Session 2: When the item is set to Page Items to Submit the same occurs. It's sent via the AJAX request, stored in APEX Session then is used in the request.

Text messages are stored for the entire application (i.e. they aren’t session specific). You shouldn’t use it to store session specific content. So I wouldn’t recommend for username.