It is called "double unary minus" and J.E. McGimpsey has some notes at:
http://mcgimpsey.com/excel/formulae/doubleneg.html

Bob Phillips explains =sumproduct() in much more detail he
http://www.xldynamic.com/source/xld.SUMPRODUCT.html

Alternate solution is
=SUMPRODUCT((conversiondataA=$A8)*(ConversiondataB =$B8)*(ConversiondataC=$C8)*(ConversiondataD=$D8), ConversiondataE)

If this post helps click Yes
---------------
Jacob Skaria


"blkane" wrote:

Below is a formula I found/developed for my use. It looks at 4 separate
criterian and sums like items together. This is used to create journal
entries of banking data into our general ledger. This was a godsend to
reduce redundant postings to my ledger.

My question is what does the character "--" do? I research sumproduct in
Excel help and it never mentioned any special characters. I only learned how
to use them from another website. However, it doesn't explain what it is or
why it makes the formula work.

Can anyone fill me in on what the "--" is? And, are there other special
characters used with this formula for other purposes? I would love to kow.

Thanks

=SUMPRODUCT(--(conversiondataA=$A8),--(ConversiondataB=$B8),--(ConversiondataC=$C8),--(ConversiondataD=$D8),ConversiondataE)