>>>Steve Sawyer has new RI code in his book (Effective Techniques for Application Development with Visual FoxPro) that will allow you to change to a different value, but I don't know if it will support NULL.
>>
>>Thanks Craig. I will take a look at it tonight.
>>
>>If Steve is doing something like this, it must be legit.
>
>It's perfectly valid for RI to do what you are asking. The example I like is, you have a salesman and he is assigned to several clients. When the salesman leaves, you can assign his clients to other people or to no one at all (NULL). The VFP RI builder does not take this into account.
>
>Another advantage of Steve's RI code is that it is more compact and efficient than the code generated by VFP's RI builder.

It doesn't seem to support NULLs in the Insert trigger with restrict option.