Using report variables to calculate subtotals in xml side [repost ]

Hello,

I'm having trouble grasping how to implement report variables and break
headers in xml.
Consider the following XML code snippet:

<Detail>
/.../

<FieldDetails>
	<Output>
		<Line bgcolor="iif(r.detailcnt%2,'0xe5e5e5','white')">
			<field value="r.field1" width="10" align="left"
col="1"/>
			<literal width="1"/>
			<field value="r.field2" width="10" align="center"
col="2"/>
			<literal width="1"/>
			<field value="val(r.field3)" format="'$%.2d'"
width="35" 
align="left" col="3"/>
		</Line>
		<HorizontalLine size="4" bgcolor="'white'"/>
	</Output>
</FieldDetails>

</Detail>

And I want r.field3 to be summed up and have a subtotal displayed at the end
of this output.  First, where do I put the following line to calculate the
subtotal?

	<Variable name="r.subtotal" value="r.total_fees" type="sum" />

Do I place it between the <FieldDetails> tags?

And then, where and how can I display the actual subtotal?  The syntax would
be very much like this, right?  I'd like it to align with the column 3
referenced between the Detail tags.
	<field value="r.subtotal" width="10" align="right" col="3"/>


-Al




-------------------------------------------------------
This SF.net email is sponsored by Demarc:
A global provider of Threat Management Solutions.
Download our HomeAdmin security software for free today!
http://www.demarc.com/info/Sentarus/hamr30