On Fri, Oct 09, 2009 at 01:04:00PM +0100, Alasdair G Kergon wrote: > So just current_area + 3? > (The first is 0, plus 2 for the header.) But the header is only 1 not 2 chunks, so finally I agree, current_area + 2. We really should get this documented... Alasdair