i agree it makes more sense on the surface. however, in the help file:
on 1:dialog:name:event:id: {
echo $dname $devent $did
}
Where name identifies the dialog, id is the id number of the control triggering the event, and event can be: ...
it seems to me that using 0 as an id is more of a kluge, to allow init events, since they're isn't a control to reference.