Altering an expression in the expression dialog automatically updates the sample results.
However, in the case of large data or complicated expression, the updating sometimes takes a long time. Clearing the [Auto update] check box, which was added in this version, stops the sample result updating allowing you to edit the expression more smoothly. When you finish altering the expression, you can click [Update] to update the sample results.

Asprova HELP -> http://lib.asprova.com/onlinehelp/en/AS2003HELP00737000.html -> [GUI]-[Dialogs]-[Expression dialog] – HelpNo.:737000