Proportional takeovers - the description of why is in the pre-AGM notes, but it is to stop a bid for shares which stops when the buyer has enough for control.
So say you have 1m and they offer 1.00, but only buy 500k from you at 1.00 and you are left with the rest at market.
It is to protect large holders where they could gain control without paying the large holder for there full holding.
