You can use the Persistent object to store
information needed for a particular user-session. Variables stored in the
Persistent object are not discarded when the user jumps between pages in the
application; instead, these variables persist for the entire user-session.
One common use for the Persistent object is to store user preferences.
For example, if a user indicates that they prefer not to view graphics, you
could store that information in the Persistent object
Var variable object name
To make a variable persistent
variable object
name(persistent)="true"
To delete a persistent variable
variable object
name(persistent)="null"