Did solve it with the following:
function make_med(int m) {
    if ! defined( bgp_med ) then bgp_med = 0;
    bgp_med = bgp_med + m;
    return true;
}
bgp_med was void even with "default bgp_med 0;"
> Hi!
> 
> Is this possible in either a import or export filter:
> 
> bgp_med = bgp_med + 3;
-- 
//fredan