How difficult it is? Optiq's Enumerable convention is efficient enough so that SUM0 provides no benefit: multiple pieces of state are handled seamlessly.
Sharing the effort might be a good thing, however I am not sure if it is worth the effort of this particular special case. I would rather implement sharing of the knowlegde "aggregate set had non-null rows", than had all those SUM0 hardcodes here and there. That is why I want to hear from Optiq users if SUM0 really helps end-users. Vladimir
