This join is exaclty what I am looking for but it relies on a calculated column "Inv #" on both sides to work.

The first column def (the one on the left) is seen for a brief moment in the video but the one on the right is never shown and has to resolve to "IN" & DOC# when the Trx type is "CA" so, clearly there is another formula hiding behind that one!

I am guessing at: IF( {Trx Type} ="CA","IN" ,"" ) & {Doc #} but it did not bind..

Thank you and,

Cheers, JK

PS: the guy who did the demo would know...