For things like the new eventClerk (and maybe filters/maps more generally) it would be useful to know which nuclide a neutron has collided with. This would require modifying the reportOutColl interface.
Doing this shouldn't be so hard, but requires a few choices to be made. First, what to do in MG simulations or when a virtual collision occurs: just send ZAID = -1? (or an appropriately defined parameter). Maybe there are other things to consider as well?