Siebel Validation rule fire when list item changed

Hi All

Kindly, i have a validation rule on Activity applet, this validation fire successfully when user submit the activity,

is there is any way to trigger the validation once list item changed, (without scripting) (using data validation rule set or any thing else from the application front end which will not require restarting the server) ,

For example:

if user change the activity status from "open" to "pending" and activity Description field is null, the error message will display to the user and the status list item will not be changed to "pending", it will remain as is "open"

Note: my Siebel is 8.1.1.10