2.1.1039 Part 1 Section 188.8.131.528, SUMIFS
a. The standard states that sum-range need not have the same size and shape as cell-range-1 through cell-range-n.
In Office, each cell-range-1...cell-range-n shall have the same size and shape as sum-range.
b. The standard states that cells in sum-range that contain TRUE evaluate to 1; cells in sum-range that contain FALSE evaluate to 0.
In Office, cells in sum-range that do not contain numeric values evaluate to 0.