Form UIBB: Check input values

Hi all,

I have a Form UIBB with a feeder class. I would like to check the values, that the user has entered. I figured out, how to send a message in method "PROCESS_EVENT" by filling table ET_MESSAGES and return EV_RESULT = 'FAILED'. But: How do I get at the values, the user entered into the form fields?

Thanks for any help in advance.

Best regards

Chris