5M570ZF256 pin out

I plan to use MAX V (5M570ZF256) in my design and want to be able to migrate to a denser device in the future so I was using the 5M2210Z.xls spreadsheet to plan my pin usage. The F256 column of that spreadsheet lists pin T6 as a GNDIO pin, but in the Quartus II Pin Planner for the 5M570ZF256 the properties of that pin are listed as DIFFIO_B6n.

Which is correct?

Thanks.