how to get a boundfield of a detailsview in javascript?

[André]

Hi,

I want
I defined a detailsview connected to a datasource. The purpose is: when an
user clicks into a particular field (when the focus is on that field),
something must happen.My problem is: how to get that field in javascript,
because i can't define an 'ID' for a boundfield.

<aspetailsView ID="DetailsView1" runat="server"
DataSourceID="SqlDataSource1" etc .../>
<Fields>
<asp:BoundField DataField="pcnr" HeaderText="pcnr" etc ...
/>
<asp:BoundField DataField="pcnr" HeaderText="pcnr" etc ...
/>
....
</Fields>
</aspetailsView>

<script language=javascript>
function foc()
{
var a=document.getElementById("??")
//var a=document.forms[0].tags(??) ...
}
....
</script>

Thanks
André