I have since discovered that the if a "required field" is omitted , it gets
checked at "Posting" time.

Here is my Idea , but it does not work :

I have since rather used "Actions" that does the job just fine, but I really
would like
to know how "THIS" must be done,, maybe this is more a concept rather than a
"IBO" related question.

Maybe some-one could post an example of explicit transaction control.

************OnClick Event Code Below ******************
try

tableAcc.Post;
tableEnq.Post;
rbUpdate1.FlushCache;

trClient.Commit;
Close; // Close the Form
except on e: Exception do
begin
trClient.RollbackRetaining;
MessageDlg('Error ', mtWarning, [mbOK], 0);
end;