The JSP Variables view shows the variables accessible by this page regardless of their origin (JSP page, Struts action, and so forth). This saves you time looking for the variables you are using in the page in the application server-specific maps!
It has five categories:
Available variables
These are the variables used by the page. The JSP Variables view can display also the variables which have not been initialized yet. To enable this feature unselect the Show Initialized Only menu item from the pull down menu.