Checking value of a field in Customer table when we open sales orde

Hi All,

I was wondering if you face the same problem.
When we open Sales Order Entry form (Sales Management\Order
Management\General Operation\Order Entry) and click on new, in sold to
group box either we search for customer id (click on id button) or
enter it in ID field. Now based on that Customer ID I want to check a
field (Customer.character06)in Customer table and if the value is lets
say "1" or whatever, then a message box pops up and tell the user to
do something like open Customer master.

When I am in developer mode and do the customization on sales order
entry, I don't see Customer table under Rule Wizard, Select View filed.

I do appreciate your help.