hide/show sections based on params

[skitty123]

I have a details section which is hidden(drilldown ok)
When I export the file to a different format I want to "show" this section so that the details get exported also.

I was thinking something like
if {?Parm1} = "1" then
True
else
False;
for the conditional suppression on the deatils section.
but how do I set this value (ie set ?param1 = 1 ) when the user clicks a button to export?

is there a better way to show/hide sections conditionaly?
please help