After you have entered an expression, you can validate and apply it.
Validation checks whether the contents of the editing pane are a proper expression. It provides a way of checking your expression's
syntax without applying it.
Applying an expression attaches it to the target parameters. Changes you make in the editing pane do not take effect until
you apply the expression.
To validate an expression
Click the button on the expression editor's command bar. A message appears in the message pane, informing you whether the expression
is valid or not.
To apply an expression
Once you have entered an expression in the bottom pane, click . The expression is automatically validated first; if it is not valid, a message informs you and the expression is not applied.
NoteClosing the expression editor applies the expression automatically.