First time I've seen any reference to such an item. Interesting.
Back in 2005 when I was shooting Provia in 4x5, I noticed after processing that each film sheet was edge lettered with a 6 letter sequence. e.g. ADCBCE, ADCBCD etc. Trust me to load my dark slides in the wrong order...
Never owned one but been in a studio/darkroom where one was used. This photographer put his name and copyright emblem on each sheet of film he used. Worked fine!.............Regards!