Excuse me for this omission. Working with RadPivotGrid templates is quite similar to RadGrid and the other databound controls. The only difference is that you don't have to use Eval. Just write Container.DataItem and then cast the result to the underlying type.
<%# (YourType)Container.DataItem == 0 ? "Yes" : "No" %>
I doubt however, that the aggregated data will return only 1 and 0 as there are not many cases (for example you can have bit field with min/max aggregate) where this would happen.
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