Ivan,

Thanks for nailing the point. Your example shows exactly why I thought
that the validation is not correct.

I was a bit surprised to read the other responses, because everyone
keeps stressing that "NULL is a state not a value", and so I thought
it is not part of *value* validation (ie. only controlled by "NOT
NULL" clause).

Anyway, according to Helen this is fixed in FB2, so I'll just be patient.

Regards,

Eyal.