hello Lester,

> So the next question has to be - what is 'linked' to that
> field. That is what control are you using to populate the
> field - which you are leaving blank. That may be 'defaulting'
> to a blank string.

there are TIB_Edit controls linked to all fields except for the
boolean field where I use an TIB_CheckBox and the date field where I
use an TIB_Date field.

I have inspected all the properties and methods of TIB_Edit but I
haven't found anything that could cause an empty string to be passed
on instead of a NULL if I leave the field blank.

Regards
Salvatore