Subject Exceptions and Error Messages

Im realtively new to IB Objects and I´m trying to find a way to show
customized Error Messages on Posting a Dataset. For Example if my
'ITEM_NUMER' field has not been entered, I want to show a message
which says
'Please enter a correct Item Numer' or similar, and not 'ITEM_NUMER
is a
required field. Is this possible?

Cheers Markus

If A = B and B = C, then A = C, except where void or prohibited by
-- Roy Santoro