On Monday 15 March 2010 22:58:41 Jim Starkey wrote:

> The basic idea that internal update operation check for declared
> events. For each declared event, it evaluates the fields in the field
> list for the before and after record versions, as appropriate.

I've implemented more or less same approach on top of DBF format around 13
years ago. The main need in it was to have a kind of RI in DBFs. It passed
all required tests, but did not go into production because the company which
wanted it and paid for it was first too lazy to use it, and later started to
use SQL servers.
Question - is there some handling of inserts and deletes? I've treated it as
changing from NULL to SomeValue for inserts and on the contrary for deletes.
It was pretty well for RI.

> It would be difficult but not impossible to implement with classic and
> straightforward to superserver.

Not too difficult - just one more shared memory object.