article numbering

I apologize, because this is not purely about TIN.

What is the maximum article number? RFC 3977 says that article numbers
must lie in 1..2^31-1 inclusive. Is this really what's going on in
the world?

What happens when a new article would have a number greater than the
maximum? Is it numbered 1? Are the starting and ending article numbers
returned by the GROUP command then reversed (the starting article number
is much higher than the ending article number)? What does TIN do in the
situation that it wants to XOVER to get new articles but an overflow
has occurred since the last time it checked?

Thanks.