if your postal code is a set length, you can use the Input Mask - either at
the table level or at the form level - to validate the characters entered.
if you set it at the table level, it carries over to any new forms you
create afterward, using that field; if you set it at the form level instead,
it only applies to the form you set it in.
as an example, U.S. postal codes are either 5 digits or 9 digits in length -
the first 5 digits are always required, but the last 4 digits (usually) are
not. so i set an Input Mask on that field as
00000\-9999;;_
that tells the system that the first 5 characters must be numbers and are
required, then show the hyphen - , then the last 4 characters must be
numbers but are not required.
the Input Mask wizard will build some standard masks for you, or you can
build custom masks yourself. to use the wizard: open the table or form, go
to the field (control, in a form), click on the Input Mask line in
Properties, and click the Build button at the right (...).
recommend that you read up on input masks, whether you build your own or use
the wizard. to do so, click on the Input Mask line in Properties, from the
open table or form, and press F1. Access Help will open to the appropriate
topic.
btw, an added bonus of using an input mask is that, in a form, you can set
the text box control's AutoTab property to Yes. then when the input mask is
filled during data entry, the cursor will automatically move to the next
object in the tab order, without the user having to hit Tab or Enter.
hth