Hard Question about DataGrid [2003/2005]

I'm using a datagrid, and I store the account number as a BOUND column.
I want it to be invisible, so I set the cell visible to false.

Easy enough, then in the code when I cycle through the datagrid items, I
find the account number by using:

Dim dgi As DataGridItem

AccountNum = dgi.Cells(1).text


When I do this, with the cell invisible, it correctly finds the account number.
But when I do a VIEW SOURCE, I see no sign of the account number in the HTML source, there is no hidden label, hidden table cell, nothing at all.
How does this work ( or IS it even working ). ???

Shouldn't the number be viewable in the html? This occurs in both VS 2003 and 2005.

I would think that this is because it is not being posted to the page. Since it is not seen on the page it wouldn't be in the code