The function of the user fields is entirely application dependent. You can use it to maintain your own application states and to pass information between Web objects running on the same agent for the same Web request (or WebSpeed transaction, if the agent is locked).
To explicitly create and access user fields, WebSpeed provides the set-user-field and get-user-field API functions. For more information on these functions, see
Passing information between Web requests. For an example of a user field used to manage a WebSpeed transaction, see
Handlingstate-aware time-outs. Also see the AppBuilder online help for syntax information.