Hi, David, it's Peter, not Markus, you see? :)
Personally I have a zero interest in Limit and don't like an idea to
cripple RDBMS for particular class of applications needs, but I can
understand web programmers. I have an idea: if FB can support for
every fetched row simply calculated (from server's position) field
(like in dataset within application), and it is not complicated task
for you, then they can handle it with between like any general column
- for application it will be "data". Forgive me if it is idea of
ignoramus.

Best regards.