Basically, I'm using SUMIFS, and the final criterion could go one of two ways: either EMER or APPC are valid values.
Here's my formula:
=SUMIFS(Data2011[Net Amount],Data2011[Internet Site],A13,Data2011[Confidence %],"B",Data2011[Ad Unit],"EMER")
The last criterion, Data2011[Ad Unit],"EMER" is...