[cctalk] Friden edge punched cards

I was just looking at some Friden Flexowriter documentation, specifically the later 2300 series. They look somewhat more modern than the well known Flexowriters but seem to be comparable otherwise. I remember seeing a mix in the TU Eindhoven computer center, around 1970. The documentation mentions an optional feature, the ability to read and punch "edge punched cards". Those look like conventional Hollerith cards, but instead of the 12 row punching with rectangular holes, they are punched along the bottom edge in exactly the same manner as an 8 channel punched tape. In other words, imagine running a blank card through the tape path of a paper tape punch, and that's what you would see. I never ran into this before. Has anyone ever seen these in the wild? paul